N over 24 = 15 over 18?

Multiplying an even number of negative numbers gives an answer that is choose from:

As a self-employed seamstress, you know that it takes 7 yards of material to make 3 jackets. you bought 15 yards of material to make 7 jackets. did you buy enough material? if not, how much were you over or under?

Mark, taylor, & brian's ages are consecutive whole numbers. mark is the youngest, and brian is the oldest. the sum of their ages is 111. how old is mark? a) 34 years old b) 35 years old c) 36 years old d) 37 years old