Each term will be 5 less than the previous term since the formula says to subtract 5.
for a expale
3, –2, –7, –12, ... is the correct sequence.
f(1) would be 3f(2) = f(1 + 1) = f(1) - 5 = 3 - 5 = -2f(3) = f(2 + 1) = f(2) - 5 = -2 - 5 = -7f(4) = f(3 + 1) = f(3) - 5 = -7 - 5 = -12
and it can keep going on