In a literal equation how do you if your supposed to divide or subtract? Please help I have a quiz tomorrow.

Aheated piece of metal cools according to the function c(x) = (.5)x ? 7, where x is measured in hours. a device is added that aids in cooling according to the function h(x) = ? x ? 2. what will be the temperature of the metal after two hours?

27 is what percent of 108? 27 is % of 108

Ineed to know the answer to this algebra question.