# Math

posted by
**Virginia**
.

I have 4 pieces of equipment that need to run one after the other. Two of them have to run at a maximum of 20 minutes each and be off a total of 90 minutes each. One of the remaining 2 peieces has to run at 15 minutes. No determined minutes off. How do I determine what the off time for this one is and the on and off time for the 4th peice of equipment?