The total cost is $30 and a quarter he had to pay five dollar entrance in $1.20 for every minute what is the equation to determine the number of minutes

Here's a rule of thumb that works for these probability questions.
Let say there are 5 objects and you can 3 of them. Then the total number of ways are:
5x4x3=60
This is because at the beginning there are 5 objects to choose from, after one is chosen, there's only 4 left. After another one is chosen, there is only 3 left. That's when you are done with your 3 turns to choose.
I am a bit busy and I will tell you later