Answer:
Esmeralda added the numerators; Esmeralda added the denominators; Esmeralda did not use the reciprocal of the divisor
Explanation:
-5 1/4 divided by 3/2 = -7/2
The same goes for the second fraction.
For the -21/4 and the 3/2 with the parenthesis, they added the numerators and denominators when they should've multiplied.
And they did not use the reciprocal of the divisor because -21/4 divided by 3/2 would mean that you would have to multiply -21/4 by 2/3 not 3/2.