How to do linear graph

What is the value of the expression below? (81^2)^1/8

For each proportion find the unknown number x 1/5/8=×/15

The chs baseball team was on the field and the batter popped the ball up. the equation b(t)=80t-16•16+3.5 represents the height of the ball above the ground in feet as a function of time in seconds. how long will the catcher have to get in position to catch the ball before it hits the ground? round to the nearest second