Hi! Can someone please help me?

What two criteria are needed for triangles to be similar

Simplify 15(x - 4)(x -1)-3(x + 4)(x - 1) with steps

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 =