Section: Math

5) The buyers club rewards for a department store card are represented through the function C(r)=4r+12, where r represents the number of purchases made with the store card. If you increase the number of purchases by 4, by how much would you increase the total rewards? 

1. 12
2. 16
3. 19
4. 23

For this answer, start by choosing any number. We'll pick 2. 4(2)+12 or 8+12=20. Now increase 2 by 4. 4(6)+12 or 24+12=36. Now subtract 20 from 36 and you're left with 16. Answer 2 is the only correct choice.