Question

What is the difference between Susan’s and Jim’s lawn-care businesses in the amounts they charge for 10 hours of work?

Answer 1

Let's assume that Susan's graph is linear. Then, we can do linear interpolation. Let y be the amount charged for 10 hours of work done:

(7-10)/(7-11) = (168-y)/(168-264)

y = $240

For Jim's Lawn care, let's find the constant slope using points (1,20) and (2,40):

m = (20 - 40)/(1-2) = 20

Then, since the y-intercept is zero, the linear equation is:

y = 20x

Substituting x = 10 hours,

y = 20(10) = $200

The difference between the two would then be:

Difference = $240 - $200 = $40