This is unsolvable because there is a contradiction. This:Only 4 walked and caught the jitney
contradicts this:10 did all three
If 10 did all three, then that means they did two. So those 10 would have had to walk and to catch the jitney. But the first statement says only 4 did. So there must be a typo here. If you want to see a problem exactly like yours, go here: http://www.algebra.com/tutors/students/your-answer.mpl?question=288071 Edwin