Hourly & Overtime wage formula needed

As of 1/1/2014, a new law for our industry will require us to pay overtime wages (time and a half) for any hours that are worked over 9 in a day. We also will need to break down the pay rate for each hour worked.

When this takes effect, we want to pay our employees the same flat rate that they are currently making. For example, we pay currently pay an employee $144 for 12 hours of work ($12 per hour). When the new law goes into effect, we want to continue to pay the employee $144, 9 of which will be be at a regular rate and 3 hour at an OT rate.

I need a formula that allows me to enter:

1. Total pay amount ($144)
2. Number of regular hours (9)
3. Number of overtime hours (3)

And it will calculate what the regular pay rate is for hours 1-9 AND what the OT pay rate is for hours 10-12.