Your answer for this would be the top one.
$420.35 = 45(n) + 60.35
The reason why is because n represents the number of months and $45 is the monthly fee therefore you have $45(n)
Then it's + $60.35 because that's the one time fee therefore it's not multiplied by anything, it's simply added to the total amount amount of whatever $45(n) is.
And obviously $420.35 is the total of it all together.