A= 100; b= 0,9
f(x)= 100.(0,9)^x
Answer: 3 
Follow the radical rule:
![\sqrt[n]{a}](https://tex.z-dn.net/?f=%5Csqrt%5Bn%5D%7Ba%7D)
= 
We get the number 
Follow the exponent rule:
= 
We get the number 
.
Now, subtract.
The answer is 3 2/3
Five points isn't worth that much tbh, but I'll still help anyways :) that's what the site is for; no need to entice people into doing your problems -- we signed up because we're happy to help!
The graph should look like this:
Days: Cost:
0 120
4 140 (120+20 in admissions)
8 160 (120+40 in admissions)
12 180 (120+60 in admissions)
16 200 (120+80 in admissions)
I hope I helped! ^u^
