Each month, Kaisorn deposits $50.00 onto her public transportation card. It costs her $2.50 per trip to ride the subway. Thom de
posits $40.00 on his public transportation card. It costs him $2.00 per trip to ride the subway. If x represents the number of trips and y represents the amount remaining in each account, which system of equations represents their transportation costs?
A 50 − 2.5x = y
40 − 2x = y
B 50 + 2.5x = y
40 + 2x = y
C 50 − 2.5y = x
40 − 2y = x
D50 + 2.5y = x
40 + 2y = x
We know that x represents the number of trips and y represents the amount remaining in each account, then, let's think in an example; after the first trip x = 1, therefore, Kaisorn's account must decrease from $50 to $50 - $2.5 = $47.5 = y, and Thom's account must decrease from $40 to $40 - $2 = $38 = y. Replacing x = 1 in each case gives:
I think the answer is D. The other answers are unreasonable. Wyatt would not get the promotion and just because Tammy's lowest value is bigger than Wyatt's doesn't mean that Tammy gets the promotion. The only reasonable answer is D.
A good way to find the answer to these questions is to find it algebraically. Let's call the first number 'n'. n + (n + 2) + (n + 4) = 54 3n + 6 = 54 3n = 48 n = 16 Therefore the numbers are 16, 18, 20