He needed to divide instead of subtracting it on the last step.

1) Let's evaluate that expression, given that a=4.9, b=-7, and c=-0.5

Note that we have rewritten it as a fraction so that we can easily operate. Also, we have applied here the PEMDAS order of operations, prioritizing the exponents.
Answer:
Area = 37.5
Perimeter = 36
Step-by-step explanation:
Have a good day! :)