Question

2x + y = 20 6x - 5y =12

Answer 1

Rearrange the first equation
2x + y = 20
take away 2x from both sides
y = 20 - 2x 
substitute this y value into the second equation
6x - 5(20 - 2x) = 12
6x -100 +10x = 12
add 100 to both sides
6x + 10x = 112
16x = 112
divide both sides by 16 
x = 7
Substitute this x value into the first equation to get y.
2(7) + y = 20
14 + y = 20
take away 14 from both sides
y = 6

So, y = 6 and x = 7

Answer 2

5(2x + y = 20) = (10x + 5y = 100)
(10x + 5y = 100) + (6x - 5y = 12) = 16x = 112
112/16 = 7

The final answer is 7.