Abulletin board is 3ft high, it's area is 15 square ft what is the perimeter of the bulletin board

Ineed solving this problem h/8=-25 solve for h idk how to this can someone show me and also give an answer you

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.

Atemperature of 1.64◦f corresponds to answer in units of ◦c.