SAT Question 1087f6c4: Linear Equations In Two Variables answer and explanation with Desmos solution

25$.It’sgiventhatthetopsoilandcrushedstoneIsabelorderedforhergardencostatotalof$$$641$. It’s also given that the equation $24.5x+24.75y=641$ represents the relationship between the number of cubic yards of topsoil, $x$, and the number of tons of crushed stone, $y$, that Isabel ordered. Since $x$ represents the number of cubic yards of topsoil ordered, $24.5x$ represents the total cost, in dollars, of the topsoil, and the cost per cubic yard of topsoil is $$24.50$. Similarly, since $y$ represents the number of tons of crushed stone ordered, $24.75y$ represents the total cost, in dollars, of crushed stone ordered, and the cost per ton of crushed stone is $$24.75$. Therefore, a ton of crushed stone cost Isabel $24.75-24.50$, or $0.25$, more dollars than a cubic yard of topsoil. Note that 1/4, .25, .250, and 0.25 are examples of ways to enter a correct answer.