Carson is going to spend 4 hours at a carnival. The wait for the roller coaster is 30 minutes, the wait for the tilt-a-whirl is 60 minutes, and the wait for the giant slide is 15 minutes. If Carson rides the roller coaster 4 times and the tilt-a-whirl once, how many times can he ride the giant slide? (Wait times include the time actually spent on the ride.)
First figure out how many minutes Carson spends at the carnival by multiplying the number of hours he's there by the number of minutes per hour: 4 hours * 60 minutes/hour = 
<gadget id="calculator">4*60</gadget>
<output>240</output>
240 minutes.
Then figure out how long Carson spends waiting for the roller coaster by multiplying the wait time per ride by the number of rides: 4 rides * 30 minutes/ride = 
<gadget id="calculator">4*30</gadget>
<output>120</output>
120 minutes.
Now subtract the time Carson spends on the roller coaster and tilt-a-whirl from the total time he spends at the park to find out how much time he has left: 240 minutes - 120 minutes - 60 minutes = 
<gadget id="calculator">240-120-60</gadget>
<output>60</output>
60 minutes.
Now divide the time Carson has left by the wait time for the giant slide to see how many times he can ride it: 60 minutes / 15 minutes/ride = 
<gadget id="calculator">60/15</gadget>
<output>4</output>
4 rides.

<result>4</result>