In the following question, select the missing number from the given responses.

$2$	$1$	$2$
$21$	$22$	$?$
$1$	$2$	$5$
$20$	$23$	$43$

The school result is increasing year after year. Forecast the result of 2012 from the following information.

How many triangles are there in the following figures?

A person distributes his pens among four friends A, B. C, D, in the ratio $\frac{1}{3}:\frac{1}{4}:\frac{1}{5}:\frac{1}{6}$. What is the minimum number of pens that the person should have?

$3$ marks for each correct sum and loses $2$ marks for each wrong sum. He attempts $30$ sums and obtains $40$ marks. The number of sums solved correctly is?

The cost of manufacture of an article was $Rs.900$. The trader wants to gain $25\%$ after giving a discount of $10\%$. The marked price should be?

Three sides of a triangular field are of length $15 m, 20 m$ and $25 m$ long respectively. Find the cost of sowing seeds in the field at the rate of $Rs.5/sq.m.$? 

Taking any three of the line segments out of segments of length $2 cm$, $3 cm$, $5 cm$ and $6 cm$,the number of triangles that can be formed is?

A contractor undertook to finish a certain work in $124$ days and employed $120$ men. After $64$ days, he found that he had already done $\frac{2}{3}$ of the work. How many men can be discharged now so that the work may finish in time?