$U\sin g\ the\ properties\ of\ proportion\ solve\ the\ \exp ression$   $\frac{\left(3x\ +\ 2\right)^2\ +\ \left(3x\ -\ 2\right)^2}{\left(3x\ +\ 2\right)^2\ -\ \left(3x\ -\ 2\right)^2}=\ \frac{5}{4}$  

 $If\ a\ :\ b=7\ :\ 8$   $find\ the\ ratio$  
 $\left(4a\ -\ \frac{b}{2}\right)\ :\ \left(4a\ +\ \frac{b}{2}\right)\$  

 $If\ x\ :\ y\ =9\ :\ 10,\ find\ the\ value\ of$  
 $\left(i\right)\ \frac{5x\ +\ 3y}{5x\ -\ 3y}$                       $\frac{2x^2+3y^2}{2x^2-\ 3y^2}$  

 $If(2y+3x):\ (3y+5x)=18\ :\ 29,\ find\ \ x^3\ :\ y^3$  

 $If\ \ \ \ 15\ (2x^2\ –\ y^2)=7xy,\ find\ x\ :\ y$  

If 2, 6, a, 54 and b are in continued proportion. Find the value of a and b.