Question 1124078
An inlet pipe can fill a tank in 15 minutes. A drain can empty the tank in 18 minutes. If the tank is empty, and both the pipe and drain are open, how long will it take before the tank overflows?
<pre>{{{matrix(1,3, 1/15 - 1/18, "=", 1/T)}}}.
Solve for T to get: {{{highlight_green(matrix(1,10, 90, "minutes,", or, 1&1/2, "hours,", or, 1, "hr,", 30, minutes))}}}