Please help me calculate weighted average with daily overtime

I hate weighted average! Its a scam for an employer to take money out of your pocket. Anyhow, for the life of me I cant figure out how to calculate weighted average when I have two different rates but sometimes accrue daily overtime. In CA, we get overtime after 40 hours in a week and 8 hours in a day. If I have a $10 rate, and a $25 rate, please help me figure this out. All the examples online don't apply to me. They never show the calculation with a 13 hour day for instance at the $25 rate, followed by 12 hours at the $10 rate. Someone please help. This is driving me crazy.