SAT Question 040f2a84: Percentages answer and explanation with Desmos solution

8$.It’sgiventhattheregularpriceofashirtatastoreis$$$11.70$, and the sale price of the shirt is $80\%$ less than the regular price. It follows that the sale price of the shirt is $$11.70\left(1-\frac{80}{100}\right)$, or $$11.70\left(1-0.8\right)$, which is equivalent to $$2.34$. It’s also given that the sale price of the shirt is $30\%$ greater than the store’s cost for the shirt. Let $x$ represent the store’s cost for the shirt. It follows that $2.34=\left(1+\frac{30}{100}\right)x$, or $2.34=1.3x$. Dividing both sides of this equation by $1.3$ yields $x=1.80$. Therefore, the store’s cost, in dollars, for the shirt is $1.80$. Note that 9/5, 1.8, and 1.80 are examples of ways to enter a correct answer.