Can someone please help me solve?

Step-by-step explanation:

sure, it's a piecewise function  and b/c they are asking for f(4)  we can just use the lower formula in the definition, soo

f(4-1) + 5.5

then f(4-1) = f(3)  where n= 3 is still greater than 1 soo

f(3-1)+5.5

f(2-1) + 5.5

f(1) = 3.5

f(4) + f(3) + f(2)+ f(1)

5.5 +5.5 +5.5+3.5=20

f(4) = 20  :)