A company sells four categories of products. Information on the daily sales for each product category is provided below. Product Category A = 304 units sold Product Categtory B = 592 units sold Product Category C = 384 units sold Product Category D = Accounts for 20% of total units sold daily across four product categories How many products are sold in Product Category D?

Let the total units sold daily across the four product categories be x. The number of units sold in category D is 20% of x $$20\%\times x=0.2x$$ Hence the equation for the total sum is $$304+592+384+0.2x=x$$ Solve for x as follows $$1280+0.2x=x$$ $$1280=x-0.2x$$ $$1280=0.8x$$ $$x=\frac{1280}{0.8}=1600$$ So the number of units sold in the category is $$0.2\times x=0.2 \times 1600=320$$ 320 units are sold in the category D.