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.
Iversonâs contribution margin ratio is 60%, so if it wants to break even, it needs to either reduce its fixed expenses by $60,000 or increase its sales by $100,000 (calculated as $60,000 loss divided by 60% contribution margin ratio).o calculate the contribution margin ratio, divide the contribution margin by sales. The contribution margin is calculated by subtracting all variable costs from sales.