Let S represent the number of hours the submarine can travel on the water's surface and U represent the number
of hours it can travel underwater in order to reach Choo
Kheng's destination,
36S + 640 > 288
2
The submarine travels for 2 hours on the water's
23
surface. What is the least number of hours the submarine
must travel underwater in order for Choo Kheng to reach
her destination?