we will write an equation that models the number of gallons, g, after t minutes

for t= 0 (at the beginning)

g(0) = 162

our unknown is the number of minutes (t) and that is what is changing. we know that it is losing 7 gallons every minutes (so 7t).

we are starting with 162 so that will be our constant - we are taking about 7 gallons each minutes therefore, our final equation will look like

g(t) = 162 - 7t

For instance, after 2 minutes, the number of gallons would be

g(2) = 162 - 7*2

g(2) = 162 - 14

g(2) = 148 there would be 148 gallons left after 2 minutes.