Answer:
32 rock songs
Explanation:
Using a proportion, or equivalent ratios, we can assign a variable to the number of rock songs and use cross-multiplication and divide to solve:
![(pop)/(rock)=(5)/(4)=(40)/(x)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/twiqt7t1ineygzt5s1pwg0mox3vpt340z6.png)
cross-multiply and divide:
5x = 4(40) or 5x = 160: 5x/5 = 160/5 or x = 32 rock songs