Can someone please explain this to me

I'm not sure I understand either have you tried the hint or video button or did that help ?

ok so to answer this question you do 2xd d=8 so you would do 2x8 which is 16 then add 3 which is 19

in problems involving proportions, we can use cross products to test whether two ratios are equal and form a proportion. to find the cross products of a proportion, we multiply the outer terms, called the extremes, and the middle terms, called the means.

hope it