To make this easier covert 1/2hours into 1/4 hours. 2 1/2 = 4/2+1/2 = 5/2. Now take 5/2 and make it 1/4th's, 5/2 = 10/4. It takes 1/4 hours to wash one car so, 10/4 divided by 1/4. Don't divide fractions so, 10/4 x 4/1, we switch the second number around to get 40/4. Now we can simplify, 40/4 = 10.
