Jose and Caroline are shopping for school supplies. Caroline spent 15.50 on 5 notebooks and 3 folders. Jose bought 4 notebooks and 4 folders and spent 14.00. What is the cost of one notebook and one folder?
+311 5n + 3f = 15.5 (1)
4n + 4f = 14 (2)
(1) * 4 = (4)
(2) * 3 = (3)
Then we get:
12n + 12n = 42 (3)
20n + 12f = 62 (4)
Subtract
8n = 20
n = 5/2 
4(5/2) + 4f = 14
10 + 4f = 14
4f = 4
f = 1
The cost of one noteboook and one folder will be 5/2 + 1 = $3.50 
