A piggy bank contains $₹ 1$1 coins, $₹ 2$ coins, $₹ 5$ coins and $₹ 10$ coins. The number of $₹ 10$ coins is four times the number of $₹ 5$ coins, eight times the number of $₹ 2$ coins and sixteen times the number of $₹ 1$ coins. If all the money in the piggy bank adds up to $₹ 555$, find the number of $₹ 10$ coins in it.

HINT: Let the number of $₹ 10$ coins be $x$. Then $10x+5\left(\frac{x}{4}\right)+2\left(\frac{x}{8}\right)+1\left(\frac{x}{16}\right)=555$

The ages of Asha and Sushma are in the ratio of 7:2. Eight years hence, the ratio of their ages will be 5:2. Find their present ages.

$[$HINT: Let Asha's and Sushma's present ages be 7x years and 2x years. 

Then $\frac{7x+8}{2x+8}=\frac{5}{2}$. Cross multiply to solve the equation.$]$

Two equal sides of a triangle are $\left(x+6\right) \mathrm{cm}$ and $\left(5x-2\right) \mathrm{cm}$. If the third side is $\left(7x-4\right) \mathrm{cm}$, find $x$. Then find the perimeter of the triangle.