Answer:
A swimming pool charges an entrance fee of $2 per person plus $0.25 for each 10 minutes they spend in the pool. How much did it cost for Katy to swim for 90 minutes?
let y = total cost
let x = number of 10 minute periods spent in pool
⇒ y = 0.25x + 2
If Katy spent 90 minutes in the pool, x = 9:
⇒ y = 0.25 x 9 + 2 = 4.25
So it cost Katy $4.25 to swim for 90 minutes.
