1. An equation for income, I = 3c + 2p, where c is the number of calendars sold and p is the number of posters sold.
2. When 25 calendars and 18 posters are sold, the income is $111.
3. Income for selling 12 calendars and 15 posters is $66.
4. 3 possible combinations; 1) 30 calendars and 5 posters. 2) 20 calendars and 20 posters. 3) 10 calendars and 35 posters.
Explanation:
Step 1; It is given that each calendar costs $3 and each poster costs $2. So if c is the number of calendars sold and p is the number of posters sold.
Total income, I = 3c + 2p.
Step 2; Now if we substitute the value of c with 25 and p with 18, we get
I = 3c + 2p = 3 (25) + 2 (18) = 75 + 36 = $111.
Step 3; If the value of p is 12 and the value of c is 15, we have
I = 3c + 2p = 3 (12) + 2 (15) = 36 + 30 = $66.
Step 4; To find combinations that cost $100, we substitute I with 100. So the equation becomes 3c + 2p = 100.
When c = 30, 3 (30) + 2p = 100, 2p = 100 - 90 = 10, 2p = 10, p =5.
When c = 20, 3 (20) + 2p = 100, 2p = 100 - 60 = 40, 2p = 40, p = 20.
When c = 10, 3 (10) + 2p = 100, 2p = 100 - 30 = 70, 2p = 70, p = 35.