Let's use f(x) for the first one and g(x) for the second.
n is the number of songs downloaded, t is the time in years, and m is the time in months.
f(x) = 125t + 10m
g(x) = 50 + n
For 2, substitute 1 for t and 12 for m.
For 4, solve f(x) = g(x).
For 5, solve g(x) for n=(14*12). Compare it to the value of f(x) for t=1 and 12=m.
