Question

31) need answer If 6x - 3y = 30 and 4x = 2 - y then find x + y.

-4
-2
0
2
4

Answer 1

Set it up as a system of equations, solve for y, solve for x, then add x+y for your answer.

Answer 2

4x = 2 - y....change to 4x + y = 2

now you system of equations is :
6x - 3y = 30
4x + y = 2 -->(3)4x + y = 2
------------
6x - 3y = 30
12x + 3y = 6 (result of multiplying by 3)
------------add
18x + 0 = 36
18x = 36
x = 36/18
x = 2
now sub 2 in for x in either of the original equations
6x - 3y = 30
6(2) - 3y = 30
12 - 3y = 30
-3y = 30 - 12
-3y = 18
y = -18/3
y = -6
Lets check it...
4x + y = 2
4(2) + (-6) = 2
8 - 6 = 2
2 = 2 (correct)

now we know that x = 2 and y = - 6.
So lets find x + y by subbing in our know values...
x + y =
2 + (-6) =
2 - 6 = - 4 --> your answer.
Do you have any questions ? If so, please ask and I will be happy to explain.