Question

A pump removes 1500 gal of water from a pool at a constant rate 40 gal/min. Which equation models the amount of water y in the pool after t minutes?

A. y = 40t + 1500


B. y = -40t - 1500

C. y = 40t - 1500

D. y = -40t + 1500

Answer 1

D, y=-40t+1500

You are subtracting 40 gallons each minute, which is why this is negative. The 1500 is positive, since this is what you have initially, and are subtracting from.

Hope this helps! :)