Ben can complete 3 math problems in 21 minutes. If he continues working at the same rate, how long will it take Ben to complete 16 math problems? thanks .
3/21 = 16/x
Cross multiply and solve for x.
3x = 336
x = 336/3
x = 112 minutes
Cross multiply and solve for x.
3x = 336
x = 336/3
x = 112 minutes