SOLUTION: A postal clerk sold 75 stamps for a total of $10.85. Some of the stamps were 15-cent stamps and the remainder of the stamps were 13 cent stamps. How many of the stamps were 13 ce

Algebra ->  Customizable Word Problem Solvers  -> Mixtures -> SOLUTION: A postal clerk sold 75 stamps for a total of $10.85. Some of the stamps were 15-cent stamps and the remainder of the stamps were 13 cent stamps. How many of the stamps were 13 ce      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


    

Question 207497: A postal clerk sold 75 stamps for a total of $10.85. Some of the stamps were 15-cent stamps and the remainder of the stamps were 13 cent stamps. How many of the stamps were 13 cent stamps?
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
A postal clerk sold 75 stamps for a total of $10.85. Some of the stamps were 15-cent stamps and the remainder of the stamps were 13 cent stamps. How many of the stamps were 13 cent stamps?
-------------------------
Quantity Equation: f + t = 75
Value Equation:::15f+13t = 1085 cents
---------------------------------------------
Multiply thru the Quantity Equation by 15 to get:
15f + 15t = 15*75
---
Subtract that from the Value Equation to get:
-2t = 1085-15*75
-2t = -40
t = 20 (# of thirteen cent stamps)
======================================
Cheers,
Stan H.