Audrey has $120 to spend on a tennis racket and lessons the racket cost $45 and the lessons cost $15 per hour define the variable then write and solve an equation to find how many hours of lessons she can afford

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.