A levee protects a town in a low-lying area from flooding. According to geologists, the banks of the levee are eroding (wearing away soil) at a rate of 3 feet per year. If something isn't done to correct the problem, what signed number indicates how much of the levee (in ft) will erode during the next decade?

The signed number that indicates how much of the levee will erode during the next decade is:

-30 feet

Step-by-step explanation:

a) Data and Calculations:

Erosion rate of the banks of the levee = 3 feet per year

For 10 years, if nothing is done to correct the problem, the eroded banks will be equal to 10 * 3 = 30 feet

Therefore, the signed erosion in the next decade is -30 feet.

b) The quantity of erosion can be given as the number of years involved without correction, multiplied by the rate of erosion per year.  This implies that the quantity of erosion depends on the number of years and the rate of erosion per year.