Question

6x+7y=79 and 7x+5y=77 so find x+2y=?

Answer 1

6x+7y = 79........(1)
7x+5y = 77.......(2)
so, multiply eqn (1) with 5 & eqn (2) with 7
and subtract (2) from (1)
30x+35y = 395
49x+35y = 539
- - -
______________
-19x + 0 = - 144
x = 7.57
putting value of x in eqn (1)
6*7.57+7y = 79
y = 0.24
so, x+2y = ?
7.57+2*0.24=8.05