How do you know that calculating 80% of the regular price gives you the same result as subtracting 20% from the regular price

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 =

Me find the value of x each figure.

Which expression is rational? 6. , square root two, square root 14, square root 49