Let
x = earnings, dollars
y = area mowed, in 1000's of square feet.
Then the required function is
y = x - 30
Construct a table that shows Derek's weekly earnings versus area mowed.
week x y
------- -------- ----------
1 204 174
2 344 314
3 450 420
4 482 452
5 504 474
----- ------- -----------
Total 1984 1834
A graph of y versus x is shown below.
From the table, obtain the total area mowed in the past five weeks as the sum of the y columns, which is 1,834 thousand square feet.
Answer: 1,834 thousand square feet.