Answer:
x = -1
Explanation:
I'm not sure I'm reading the problem correctly, the "table" didn't survive formatting changes.
BUT if the question is what input value X produces the same output Y then this is pretty straightforward forward and you don't even need the table.
Basically, the question is asking what number, when substituted for X, produces the same result.
That tells us that x + 7 = 2x + 15
Solve for x:
x = -8
f(x) = {x+7}
g(x)=2x+15
f(-8) = ((-8) + 7) = -1
g(-8) = (2(-8) + 15) = (-16) + 15 = -1
x = -1