This question is fairly straightforward, but the arithmetic for equation
52x+ 58y = 492 would be very challenging. In the solution section it says
"Therefore she must have sold 9 lemonades, and since there will only be one combination of small and large lemonades that will work out to 4.92"
My question is that how do you know there is only one combination.
We would still have to work through all of the combinations of x,y between 0-9 to verify if there is only one combination. If there is more than one, then we cannot select B. I dont understand how the person can make the assumption that there is one solution. But to verify it would take a lot of time on the test.