For the first one you plug the second equation into the first so substitute the y with x + 7 so you have -6x-5(x+7)=9 and you get -11x-35=9 and then you have -11x=44 and so x=-4 and the you plug -4 into y = x+7 and so y would be 3.
The next question you can turn -7p-35 to -7(p+5) and then cancel out the -7 on both sides and get p+5=3p-3 and then you -p and +3 both sides and get 2p=8 and so p = 4
you can plug the numbers just to double check