If the ratio of students who prefer coke to Pepsi is 5 out of 7, it means that out of any total of surveyed students, 5/7 of the total prefers Pepsi, and 2/7 of the total doesn't.
So, out of 84 students, the number of those who prefer pepsi is
[tex] 84 \times \dfrac{5}{7} = \dfrac{84\times 5}{7} = 60 [/tex]
