Who already learned algebra?

I did im in algebra 1 now

The equation is if f (1) = 7 and f (n) = f (n-1) - 4, then find f (6)

basically we see that to get a term (f (n)), we subtraction 4 from the prevous term (f (n-1))

so see how many times we need to subtract

6th term, so 5 times (don't subtract of first tiem)

5*4=20

7-20=-13

f (6) = - 13