From Wikipedia, the free encyclopedia. Phototoxicity, also called photoirritation, is a chemically induced skin irritation, requiring light, that does not involve the immune system. It is a type of photosensitivity. The skin response resembles an exaggerated sunburn.
Contribution margin ratio measures the percentage of sales that would increase net income. To calculate it, divide contribution margin by sales, either in total or per unit: Suppose a gadget selling for $100 per unit brings in $40 per unit of contribution margin.
Contribution Margin Increase. The contribution margin ratio increases when sales increase. For every $1 increase in sales, profits increase by the contribution margin ratio. For example, if a companyâs contribution margin ratio is 25 percent, it is earning roughly 25 cents in profit for every one dollar in sales.ay sales increase to $150, while fixed expenses remain unchanged and variable expenses increase to $90. This increases its contribution margin ratio to $60 / $150 = .40 or 40 percent.