I am having difficulty with this problem. Can someone EXPLAIN the steps on how you arrive at the answer so that I can understand this?

Here is the problem:

Evaluate the definite integrals using the graph of fife} below. 2 [a] f{a:} dz : Number I] 4 [h] f{t} d3 = Number 2 T [c] f{:{:} (in: : Number