Step-by-step explanation:
Substitute the y in the 1st equation with the 2nd equation.
7x + 10(2x + 9) = 36
7x + 20x + 90 = 36
27x + 90 = 36
3x + 10 = 4
3x = -6
x = -2
So now we can find y.
y = 2x + 9 = 2(-2) + 9 = (-4) + 9 = 5.
So x = -2, y = 5.
400 should be the answer. Hope this helps!
1) subtract 2y in both sides: (7y-2y)-6=(2y-2y)+8 which is 5y-6=8
2) Add 6 to both sides: 5y(-6+6)=8+6 which is 5y=14
3) Divide 5 on both sides: 5y/5=14/5 which is y=14/5 or y=2.8 or y=2 4/5