Question

x - 3y = 0

2x + y = 5

Answer 1

 x - 3y = 0  x = 3y  ==> x = 3(5/7) ==> x = 15
2x + y = 5                                                  7

 2(3y) + y = 5
   6y + y = 5
   7y = 5

   y = 5/7