Final answer:
The correct equations for determining the total cost of cell phone plans for 300 minutes are provided.
Step-by-step explanation:
The correct equations that could be used to determine the total cost for each plan for 300 minutes are:
Spirit (s): s = 0.05x + 20
Horizon (h): h = 0.15x
For the Spirit plan, the fixed fee is $20, and there is an additional charge of 5 cents per minute. So, we multiply the number of minutes (x) by 0.05 and add 20.
For the Horizon plan, there is no fee, and the charge is 15 cents per minute. So, we multiply the number of minutes (x) by 0.15.