John can service a television and a cable box in one hour. it took him four hours yesterday to service two televisions and ten cables boxes. how many minutes does john need to service a cable box? show work

It's 15 minutes, because it takes 1 hour for a television and a cable box, so you take 2 hours from the 4 hours, from the 2 televisions and the 2 cable boxes, so now you got 2 hours left and 8 cable boxes, so 2 hours is 120 minutes, and 8÷120=15