I believe the answer your looking for is B.. good luck my friend!
distribute the 8 to the 5 and x. then distribute 11 to 9 and x.
(40+8x)=(99+11x)
-11x -11x
-3x+40=99
-40 -40
-3x= 59
divide three on both sides
x=59/-3
final answer x=-59/3
I would combine then solve.
The choice D is in scientific notation
7.8*10^5