Answer:
There are 6 rock songs on Fernando's road trip playlist.
Step-by-step explanation:
Given that he keeps the ratio same
This means that the ratios for both summer playlist and trip playlist will be the same
Let
c1 be the country songs in summer playlist
r1 be the rock songs in trip playlist
Similarly,
c2,r2 will be the country and rock songs in trip playlist
Both will be equal so

Putting the values

Hence,
There are 6 rock songs on Fernando's road trip playlist.
174 is the missing number
Well area of a triangle is

so,

The answer is 8
Your translation is "to solve or decide" hope this helps!