Advanced Mathematical Decision Thinking Semester 2 Pre-test
19. You charged $658.17 on your new credit card for your college textbooks. Your credit card has
an introductory APR of 6.8% for the first 6 months which gave you a monthly payment of
$111.88. Assuming you managed to pay off the credit card in 6 months, how much of what
you paid back was interest?
A. $11.13
B. $671.28
C. $13.11
D. $680.86

$5

Step-by-step explanation:

Let the cost of one burger be $b while the cost of one small fries be s

2 burgers and 2 small fries cost $14

This means that;

2b + 2s = 14

divide both sides by 2

b + s = 7 •••••••• (i)

Three burgers and four small fries cost $23

Mathematically;

3b + 4s = 23 •••••••• (ii)

From i , we can see that s = 7- b

we can now substitute this into equation ii

3b + 4(7-b) = 23

3b + 28 -4b = 23

4b -3b = 28 -23

b = $5

one burger costs $5