Noah invested $ 2500 in an account paying 3.5 percent sign simple interest. How much was his account worth after 5 years

An arrow is shot vertically upward at a rate of 180ft/s. use the projectile formula h=−16t2+v0t to determine at what time(s), in seconds, the arrow is at a height of 420ft. round your answer(s) to the nearest tenth of a second.

How can i differentiate this equation?

The answer is 7.2 how would you put this as money