A) -9
-7(x+9)=9(x-5)-14x
-7x-63=9x-45-14x
-45 -45
-7x-18=9x-14x
+7x +7x
-18=9x+7x-14x
-18=2x
(-18)/2=(2x)/2
-9=x
It can help because 9×4 =36, and 9×8=72. if you divide 72 by 2 you get 36 which is the answer to 9 ×4. basically because nine is the same in both problems you are multiplying by 4 (and you know 4 is half of 8) you can assume that multiplying the sum of 4 and 9 that you will get the sum of 8 and 9.
