A total made from a repeating charge and a one-time fee can be modeled by a one-variable equation, an equation with one unknown. “For each visit” tells you which charge to multiply by the visit count. Add the one-time fee once, then enter the equation as a Desmos regression. Counting one too many or one too few visits changes the fee you find.
Hints
- Hint 1
A per-visit charge repeats each time Jamie visits. Multiply the price of one visit by the number of visits. What part of her monthly total does that product represent?
- Hint 2
A fixed fee is paid only once, no matter how many visits Jamie makes. Add it to the cost of all her visits to match the total. Keep all 9 visits in your equation.
Step-by-step
Model the charge, then solve in Desmos
Step 1Write the equation for the total charge
Jamie made 9 visits at $12 each, so the visits cost dollars. The fixed fee is paid once. Together, those charges make the $168 total:
Use 9 visits, not 8 or 10. Multiply the charge that repeats, but add the one-time fee once.
- Step 2
Find the enrollment fee
Type in Desmos. The makes a regression: Desmos finds the value of that makes both sides equal, rather than making a slider. Under PARAMETERS, it shows . So Jamie's enrollment fee was $60. Choice C.