Question

If 3x + 5y = 9 and 5x + 3y = 7, then find the value of x + y.

Answer 1

Given, 3x + 5y = 9  ......(i)

5x + 3y = 7  ......(ii)

On adding equations (i) and (ii), we get

   3x + 5y = 9
+ 5x + 3y = 7   
   8x + 8y = 16

∴  8(x + y) = 16

x + y = `16/8` = 2

∴ x + y = 2