Help asap(will gove thanks and brainlist)(simplify the expression into a exponent)

For one history test, keith had to answer 40 questions. of these 40 questions, keith answered 28 of them correctly. what percent did keith get on his history test? round your answer to the nearest tenth if necessary

Anyone? 15m is what percent of 60m; 3m; 30m; 1.5 km?

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?