how do i do this problem?

Cullumber Corporation sells three different models of a mosquito "zapper" Model A12 sells for $64 and has unit variable costs of $45. Model B22 sells for $128 and has unit variable costs of $90. Model C124 sells for $512 and has unit variable costs of $384. The sales mix(as a percentage of total units) of the three models is A12, 60%; B22. 15%; and C124.25% What is the weighted average unit contribution margin? (Round answer to 2 decimal places, s. 15.50) Weighted Average Unit Contribution Margin $