Question

Sarah bought 8 folders and 3 rulers. Lea bought 8 rulers and 3 folders. Sarah paid $1.25 more than Lea. How much was each folder if each ruler was .45 cents

Answer 1

8f+3r = 8r+3f + 1.25
now plug in r=.45 to get
8f+1.35 = 3.60+3f+1.25
5f = 3.50
f = .70

check:
8*.70+3*.45 = 6.95
3*.70+8*.45 = 5.70
difference is 1.25

Answer 2

.70