Answer:
Correct solution in steps
- 5 - 2(a + 7) + 10a = The first operation is parenthesis
- 5 - 2(a) - 2(7) + 10a = The second operation is simplification
- 5 - 2a - 14 + 10a = Next operation is collecting like terms
- (10a - 2a) + (5 - 14) = Next operation is simplification
- 8a + (-9) =
- 8a - 9
The error in the given solution was the first step: (5 - 2)
