Maximum approximation

What is the problem with this question? I'm crying.
I'm trying to understand the maximum approximation algorithm of https://doc.lagout.org/science/0_Computer%20Science/2_Algorithms/Approximation%20Algorithms%20%5BVazirani%202010-12- 01% 5D.pdf. I am not able to understand how to apply this to the example. Can any one explain how to apply this algorithm to the example clauses 4 and how to achieve a ratio of 3/4?

edit1: the algorithms are in chapter 16. section 16.4.