Please help me math the formula for prorate

[Coby]

Greeting, please help me math a formula to prorate by 10 mins the hourly rate of the room and the amount of guests on a timer. Column H will display the sum of both rates based on the duration of the timer. I cannot math. Thank you for the input.

Here is my layout:

Screen Shot 2019-08-22 at 4.15.11 AM.png

[JeteMc]

Hello Coby and Welcome to Excel Forum.
Since the hourly rate isn't given and since we don't know whether to multiply or divide the prorated amount by the number of guests, these are general formulas, meaning that you'll need to choose the appropriate formula and fill in the hourly rate.
1. If multiplied by number of guests: =hourly rate*MROUND(C3,TIME(0,10,0))/TIME(1,0,0)*E3
2. If divided by the number of guests:=hourly rate*MROUND(C3,TIME(0,10,0))/TIME(1,0,0)/E3
Let us know if you have any questions.