Can anyone help me solve this

Answer:
a. $45.54; b. $51.42; c. See below
Step-by-step explanation:
a. 193 min
Service charge = $40.00
1st 100 min @ 0.021 = 2.10
Next 93 min @0.037 = 3.44
Total = $45.54
b. 317 min
Service charge = $40.00
1st 100 min @ 0.021 = 2.10
2nd 100 min @ 0.037 = 3.70
117 min @ 0.048 = 5.62
Total = $51.42
c. Piecewise function
The charge is
which we can write like this:
[tex]f(t) =\begin{cases}40.00 + 0.021t & t \leq 100\\42.10 + 0.037(t-100) & 100 < t \leq200\\45.80 + 0.048(t-200) & t > 200\end{cases}[/tex]