Can you help me with this Real Analysis problem, please?(Can you have the answer written on paper too, please? I feel like I can read it easier that way. Thank you very much!)

Exercise 5.3.3. [Used in Exercise 5.3.4, Example 5.5.2, Section 6.4, Exercise 6.4.3 and Example 10.2.4.] Let [a, b] C & be a non-degenerate closed bounded interval, and let f.g: [a.b] & be functions. (1) Suppose that f is zero except at one point. Prove that f is integrable and that 12 f(x)dx=0