Help with this I don't know how to solve.

Does y+x=1 show direct variation. yes or no.

Jason jumped off of a cliff into the ocean in acapulco while vacationing with some friends. his height above ocean measured in feet as a function of time could be modeled by the h(t) = -16t2 + 16t + 480, where t is the time in seconds from jumping off. how high is the cliff in feet?

Evaluatethe expression 7.5-3.2+4(raised to the third power) / 2