Question

2x+3y=12 and 2x-y=4 what is the value of x+y

Answer 1

2x + 3y = 12
2x - y = 4 ====>multiply by -1
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2x + 3y = 12
-2x + y = -4 (result of multiplying by -1)
------------add
4y = 8 -- divide by 4
y = 2

now sub 2 in for y in either of the equations to find x
2x + 3y = 12
2x + 3(2) = 12
2x + 6 = 12 -- subtract 6 from both sides
2x = 12 - 6
2x = 6 -- divide by 2
x = 3

check..
2x - y = 4
2(3) - 2 = 4
6 - 2 = 4
4 = 4 (correct)

Now that we know x = 3 and y = 2, we can finish the problem..
the value of x + y = 3 + 2 = 5