What is 2 1/2 x 3 I really need the answers I have a big test

Tom can paint the fence in 12 hours, but if he works together with a friend they can finish the job in 8 hours. how long would it take for his friend to paint this fence alone?

Math i have no idea how to do a and b

The amount of data left on the cell phone six gb for 81.5 gb of data is used how much data is available at the beginning of the cycle