Im am trying to figure out how to compute contribution margin ratio. I found the sales mix percentage, but where do I go from there. You can use whatever numbers you want as long as you can give me a break down on how to compute the contribution margin ratio

Sales 100
Variable Costs (60)
Contribution Margin 40
Fixed Costs (10)
Net Income 30

Contribution Margin = Sales – Variable Costs = 100-60 = 40
Contribution Margin Ratio = (Sales – Variable Costs) / Sales = (100-60) / 100 = 40%