Elapsed time of one hour and 12 minutes ends at 3:31 PM what was the start time?

In triangle △abc, ∠abc=90°, bh is an altitude. find the missing lengths. ah=4 and hc=1, find bh.

Awater holding tank measures 105 m long, 50 m wide, and 8 m deep. traces of mercury have been found in the tank, with a concen- tration of 60 mg/l. what is the total mass of mercury in the tank? answer in units of kg.

James was playing a game with his friends. he won 35 points. then he lost 15, lost 40 and won 55. how did he come out