Which of the following expressions are equivalent to 4^-3/4^-8?

Aball is thrown from a height of 139 feet with an initial downward velocity of 15 ft/s. the ball's height h (in feet) after t seconds is given by the following. h=139-15t-16t^2 how long after the ball is thrown does it hit the ground? round your answer(s) to the nearest hundredth. (if there is more than one answer, use the "or" button.) t =

Gabrielle's age is two times mikhail's age. the sum of their ages is 84. what is mikhail's age?

Pls the last one and it has to be like number 6