Please help me fast!!( It's about writing linear equations from a graph)

Given: x + y = 6. if xe (-15, -6, -1), then which of the following sets of ordered pairs are solutions? © {(-15, -21), (-6, -12), (-1, -7)} [(-15, 21), (-6, , 7)} {(-15, 21), (-6, 12), (-1, -7)}

For which pair of functions is (gof)(a)=|a|-2?

How to do this , and can some one explain