what you do is to substitute the first number for x and the second for y:
(x+7)y=10
a):
(-9+7)*-5=10
(-2)*-5=10
10=10
yes, it's a solution!
b)
(-8+7)10=10
-1*10=10
-10=10
no, not a solution!
c) (-2+7)2=10
5*2=10
yes, a solution!!
d) (3+7)*5=10
50=10
no, not a solution!