16 classes have 25 students each which EQUALS a total of 400 students and 3 classes which each have 100 students each which EQUALS a total of 300 and 1 class has a total of 300 students and the total number of students is 1000
D is right because there is not tire
I would assume that you convert 2.5 ounces into punds which would make it 0.15 lbs.

Negative multiply negative = Positive
Negative multiply positive = negative

Thus the answer is -4a + 16b - 12c - 12d.