At an amusement park, players can sue tickets that they won playing skeeball and other games to trade for prizes. Each ticket is worth 3, 7, or 15 points. If you can trade 10 15-point tickets for x pairs of x-ray goggles, how many pairs of x-ray goggles can you trade for s 7-point and t 3-point tickets?
10*15 = 150
(7s+3t)/150