The ice skating rink charges an hourly fee for skating and $3 to rent skates for the day. Gillian rented skates and skated for 3 hours and was charged $21. Which equation represents the cost, c(x), of ice skating as a function of x, the number of hours of skating?

c(x) = 3x + 3
c(x) = 6x + 3
c(x) = 7x + 3
c(x) = 8x + 3

1 answer

To determine the equation that represents the cost \( c(x) \) of ice skating, we need to understand the components of the cost.

  1. There is a $3 fee to rent skates.
  2. There is an hourly fee charged to skate for each hour.

Let \( x \) be the number of hours skated. The total cost \( c(x) \) can be expressed as:

\[ c(x) = (\text{hourly fee}) \times x + \text{skate rental fee} \]

From the information given, we know that Gillian skated for 3 hours and the total charge was $21, which can be expressed as:

\[ c(3) = 21 \]

Substituting the equation for \( c(x) \):

\[ c(3) = \text{Hourly fee} \times 3 + 3 = 21 \]

Let’s denote the hourly fee as \( y \). We can set up the equation:

\[ 3y + 3 = 21 \]

Subtracting 3 from both sides:

\[ 3y = 18 \]

Dividing by 3:

\[ y = 6 \]

So the hourly fee is $6. Now we can write the cost function:

\[ c(x) = 6x + 3 \]

Thus, the equation that represents the cost of ice skating as a function of \( x \) is:

\[ c(x) = 6x + 3 \]

Therefore, the correct choice is:

c(x) = 6x + 3