The rate of depreciation of a building is given by D'(t) = 4000(10 t) dollars per year, 0 t 10; see the following figure.

A coordinate plane is given. The horizontal axis is labeled tand the vertical axis is labeled D'(t). A line and a shaded region are graphed.

• The line labeled D'(t) starts at (0, 40000), goes down and right, passes through (5, 20000), and stops at t = 10 on the positive t-axis.
• The area under the line from t = 0 to t = 5 is shaded.

(a) Use the graph to find the total depreciation of the building over the first 5 years

(t = 0

to

t = 5).

$ (b) Use the definite integral to find the total depreciation over the first 5 years. $