SAT Question 2a549721: Area and Volume answer and explanation with Desmos solution

Choice B is correct. The area $A$ of a rectangle is the product of its length $l$ and its width $w$. It follows that $A=lw$. It’s given that rectangle $ABCD$ has an area of $280$ square centimeters and the length of the rectangle is $10$ centimeters. Substituting $280$ for $A$ and $10$ for $l$ in the equation $A=lw$ yields $280=10w$. Dividing both sides of this equation by $10$ yields $28=w$. Therefore, the width, in centimeters, of the rectangle is $28$.