Explanation for Question 18 From the Math (Calc) Section on the 2020 March Sat
So let's read question 18. It tells us that a sports store has 60 2 backpacks in stock. So total of 60 backpacks, 3 some with wheels and some without wheels before a new shipment arrives and the 4 number of wheeled backpacks. Right? 5 So wheeled backpacks is twice the number of wheel backpacks 6 already in stock. And the number of backpacks without wheels in the new shipment 7 is five times the number already in stock. 8 And it tells us that after the new shipment arrived, there were 330 backpacks 9 in the store, right? So we started with 60. Then we got a new 10 shipment and we got 330 backpacks. 11 So if we did the quick math, right, 12 30 minus 63, 30 minus 60, 13 we added 270 backpacks. 14 Um, and so it tells us after they were here, 15 um, before the shipment, there were X wheeled and there were w X 16 wheeled and why without wheels, um, 17 and which of the following can be used with this equation to solve for 18 X and Y. 19 So what you'll see is that this equation that they've already given us represents 20 how many backpacks were in the store before the new shipment, 21 right? So our equation that we're coming up with should have represent the new 22 shipment, not the total, 23 right? We can't do the total, um, 24 because that would have, that would have been X plus two X plus Y 25 plus five, Y is equal to the 330. 26 But what we can do is use the amount that we're in the shipment, 27 the number of backpacks, which was two 70 to come up with a new 28 equation. And if w...