Can someone please help me thank youu

Question: what is the value of x 4x-2= (-7) +5x. it would be greatly appreciated if someone could actually explain to me step by step

What is the number 321,000,000 in scientific notation? also what is the number? ?

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 =