In a certain type of brass the ratio of measurements of Copper and Zinc is $5:2$. Let's work out what will be the ratio of Copper and Zinc in $28 \mathrm{kg}$ of brass if $4 \mathrm{kg}$ of Copper is added to it. 

There is a tea-stall of Nilmoni uncle at the crossing of our locality. My brother and I often go to uncle's stall after our study and help him in many ways. Today we have also gone there. We have seen that Nilmoni uncle was mixing some Darjeeling tea with Assam tea in a casket. 

In the casket $1$, the ratio of the quantities of Assam tea and Darjeeling tea is $5:2$

In Casket No. $2$ the ratio of the quantities of Assam tea and Darjeeling tea is $2:1$

Then, the quantity of Darjeeling tea out of $21 \mathrm{kg}$ of blended tea in Casket No. $1$ is _____ $\mathrm{kg}$.

There is a tea-stall of Nilmoni uncle at the crossing of our locality. My brother and I often go to uncle's stall after our study and help him in many ways. Today we have also gone there. We have seen that Nilmoni uncle was mixing some Darjeeling tea with Assam tea in casket No.$1$

In casket No. $1$ the ratio of the quantities of Assam tea and Darjeeling tea is $5:2$

In casket No. $2$ the ratio of the quantities of Assam tea and Darjeeling tea is $2:1$

Let's calculate the quantities of Assam tea and Darjeeling tea out of $21 \mathrm{kg}$ of blended tea in casket No. $2$

Answer:
The quantity of Assam tea out of $21 \mathrm{kg}$ of blended tea in casket no $2$ is$=\boxed{?}\times \frac{2}{3} \mathrm{kg}=\boxed{?} \mathrm{kg}$ 

And the quantity of Darjeeling tea is $=\boxed{?}\times \frac{1}{3} \mathrm{kg}=\boxed{?} \mathrm{kg}$

There is a tea-stall of Nilmoni uncle at the crossing of our locality. My brother and I often go to uncle's stall after our study and help him in many ways.

Today we have also gone there. We have seen that Nilmoni uncle was mixing some Darjeeling tea with Assam tea in casket No.$3$

In casket No. $3$ the ratio of quantities of Assam tea and Darjeeling tea is $3:2$.

Let's work out the quantities of ratio of Assam tea and Darjeeling tea if additional $7 \mathrm{kg}$ of Assam tea is mixed with $25 \mathrm{kg}$ of blended tea in casket No. $3$. 

Answer:
The quantity of Assam tea in casket No. $3$ is  $25 \mathrm{kg}\times \frac{3}{5}=15 \mathrm{kg}$

And the quantity of Darjeeling tea is $25 \mathrm{kg}\times \frac{2}{5}=10 \mathrm{kg}$

Total quantity of Assam tea after mixing $7 \mathrm{kg}$ of that of the same $=\boxed{?} \mathrm{kg}$ 

Now the quantity of Assam tea: the quantity of Darjeeling tea out of the blended tea in casket No. 3 is $22:10=11:5$
 

There is a tea-stall of Nilmoni uncle at the crossing of our locality. My brother and I often go to uncle's stall after our study and help him in many ways.

Today we have also gone there. We have seen that Nilmoni uncle was mixing some Darjeeling tea with Assam tea in casket No.$3$

In casket No. $3$, the ratio of quantities of Assam tea and Darjeeling tea is $3:2$ and the quantity of mixture is $25 \mathrm{kg}$.

Instead of mixing $7 \mathrm{kg}$ of Assam tea with the blended tea in casket No. $3$, $2 \mathrm{kg}$ of Darjeeling tea would have been mixed.

Let's work out what the ratio of measurement of Assam tea and Darjeeling tea would be in the new blend. 

There is a tea-stall of Nilmoni uncle at the crossing of our locality. We have seen that Nilmoni uncle was mixing some Darjeeling tea with Assam tea in a casket. In this casket, the ratio of the quantities of Assam tea and Darjeeling tea is $5:2$ and total quantity of mixture is $21 \mathrm{kg}$. What quantity of Darjeeling tea in $\mathrm{kg}$ needs to be mixed with the blended tea in the casket, so that the ratio of measurements of Assam tea and Darjeeling tea will be $5:3$?

There is a tea-stall of Nilmoni uncle at the crossing of our locality. My brother and I often go to uncle's stall after our study and help him in many ways. Today we have also gone there. We have seen that Nilmoni uncle was mixing some Darjeeling tea with Assam tea in casket No.$2$

In casket No. $2$, the ratio of the quantities of Assam tea and Darjeeling tea is $2:1$ and total quantity of mixture is $21 \mathrm{kg}$.

Let's calculate what quantity of Darjeeling tea needs to be mixed with the blend in casket No. $2$. so that the ratio of Assam tea and Darjeeling tea will be $7:4$ in the new blend.