math
posted by jade .
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?

Let the folders cost f.
Let the rulers cost r.
Sarah paid: 8f + 3r
Lea paid: 8r + 3f
Sarah paid 1.25 more than Lea.
8f + 3r = 1.25 + 8r + 3f
5f = 1.25 + 5r
f = 0.25 + r
The rulers cost: r = 0.45
.: f = 0.70
Each folder costs 70 cents.
Check.
8*(0.70) + 3*(0.45) = 6.95
1.25 + 8*0.45) + 3 *(0.70) = 6.95
Okay!