42.3952 to the nearest thousandths

Aswimming pool has an input pump for filling the pool and an output pump for emptying the pool. the input pump can fill the pool in 3 hours, and the output pump can drain the pool in 5 hours. as you go to bed, the pool is full, but a neighbor’s kid turns on the output pump. at midnight, you awake to find the pool half empty. immediately, you turn on the input pump, but you are sleepy and forget to turn off the output pump. at what time will the pool become full?

Li buys supplies so he can make and sell key chains. he begins to make a profit only after he sells 4 key chains. what point on the graph makes the most sense in this situation?

What is the effect on the graph of the function f(x)=x when f(x) is replaced with -f(x)+4