A fee paid once plus a charge “per mile” signals a linear model: total cost is the fixed fee plus the per-mile rate times the distance. Write that relationship before calculating, then use Desmos for the fare. Multiplying the rate by the distance gives only the travel charge; stopping there leaves out the booking fee.
Hints
- Hint 1
A fixed fee is paid once, even if the distance changes. A charge “per mile” repeats for each mile. Which part of the fare should you multiply by the number of miles?
- Hint 2
A rate in dollars per mile turns miles into dollars when you multiply. That product is only the travel charge. What amount must you add to get the total cost?
Step-by-step
Add the fixed fee to the travel charge
Step 1Write the cost rule
Let be the miles traveled. The rate of $1.80 per mile contributes , while the booking fee of $2.90 is paid once. So multiply only the per-mile charge by the miles:
- Step 2
Find the travel charge
For 14 miles, type in Desmos. It shows , or $25.20. That's the travel charge, not yet the total.
- Step 3
Add the booking fee
Add the one-time fee to the travel charge: type in Desmos. It shows , or $28.10 to the cent. So the total cost for the 14-mile ride is $28.10. Choice D.