We have defined in the problem the time in minutes, but the requirement is give the formula in seconds, then
1minute = 60seconds,
a) In one hand we have,
[tex]f(s) = A(s)[/tex]
Where s is the time in seconds and A the altitude. How S is a medition given in minutes, we convert,
[tex]f(s) = A (\frac{s}{60})[/tex]
b) In the other hand we know that
[tex]1minute = \frac{1}{60}[/tex]hours, then
[tex]f(s) = A (60h)[/tex]