Brothers WeiWei and RenFei wanted to detail their mom's car. It took WeiWei 12 Hrs to finish the job. If RenFei had helped from the start, the job would have been completed only in 3 Hrs. Working alone, ReinFei will take how many Hrs to detail the car?
TJ test prep practice problems for our students and readers. The problems provide a very small sampling of what Optimal TJ Prep students work with.