Kopano makes calls during business hours and needs to upgrade his cell phone contract. He has two options to choose from: Business contract and Prepaid option. Use the table provided to answer the following questions.

3.1
One advantage of using the prepaid option is that there is no monthly subscription fee.

3.2 (or 3.12)
Let $t$ be the total peak minutes used per month.
The formula Prince could use to calculate the total cost of using the business contract is
$Total cost (R) = 120 + 1.50(t - 120)$
for $t > 120$.
(For $t \leq 120$, total cost = R120.)

3.14
Independent variable: Total minutes used per month, $t$ (minutes)
Dependent variable: Total cost, $C$ (R)

3.16
The y-intercept represents the total cost when no minutes are used ($t = 0$), which is the fixed monthly subscription fee of R120 for the business contract.

3.17
On the graph:

• Business contract: Horizontal line at $C = 120$ from $t = 0$ to $t = 120$, then line with slope 1.50 starting from (120, 120).
• Prepaid option: Straight line through origin (0,0) with slope 1.90, equation $C = 1.90t$.
  Draw both lines on the same set of axes.