SAT Question 0c490cd5: Linear Functions answer and explanation with Desmos solution

Choice C is correct. It's given that Sam has a flag with an area of $110$ square inches (${\text{in}}^2$) and that each piece of colored nylon Sam sews on increases the flag's area by $64{\text{in}}^2$. If Sam sews on $x$ pieces of nylon and each piece increases the area by $64{\text{in}}^2$, it follows that the expression $64x$ represents the total increase in area, in square inches, from sewing on $x$ pieces of nylon. Adding this increase in area, $64x{\text{in}}^2$, to the original area of the flag, $110{\text{in}}^2$, gives the total area of the flag. Therefore, the equation that gives the flag's total area $y$, in square inches, after Sam sews on $x$ pieces of nylon is $y=110+64x$.