It looks like you had some of the numbers correct, but you just labeled it and rounded it incorrectly, and the teacher gave you super partial credit for it.
For my work, I'm assuming that side A is opposite of angle A and side B is opposite of angle B, etc...
I believe you would have to multiply both 25 and 20 and what ever number you get dived by 100 if the numbers to high multiply aging or subtract the number (if it's wrong I'm really not good at my math I'm sorry)