exercise:

Two producers in a market producing widgets have different marginal abatement costs: MAC1=2A1

MAC2=3A2

Where A is units of abatement, NOT EMISSIONS, in tons per year, and P is price in $/ton. The demand/marginal benefit for abatement is as follows: MAB=22-A

Question:

What is the aggregate MAC function for the Widget market (at a given price, how much will be abated?)

Possible answer: I know that to get the aggregate MAC function I should sum up horizontally.. so I clear the equation for each producer .. and I get 5/6 as a result of A. Then if I set the price $10 ... how can I calculate the abatement cost? 5/6 times 2 for the MAC1 and time 3 for the MAC2?

Am I correct???