Explain how to calculate a unit rate such as 300 miles per hour 4 hour my brain is not working today i need help

At a sale this week, a desk is being sold for $213. this is a 29% discount from the original price. what is the original price?

Aman is 6 feet 3 inches tall. the top of his shadow touches a fire hydrant that is 13 feet 6 inches away. what is the angle of elevation from the base of the fire hydrant to the top of the man's head?

What is x and y intercepts for y=x+7