SOLUTION: Ruth purchases some $.01 stamps, some $.15 stamps and some $.20 stamps. She has spend a total of $5.00. There are three times as many $.01 stamps as $.20 stamps and 8 more $.15 s

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: Ruth purchases some $.01 stamps, some $.15 stamps and some $.20 stamps. She has spend a total of $5.00. There are three times as many $.01 stamps as $.20 stamps and 8 more $.15 s      Log On


   

Question 162881: Ruth purchases some $.01 stamps, some $.15 stamps and some $.20 stamps. She has spend a total of $5.00. There are three times as many $.01 stamps as $.20 stamps and 8 more $.15 stamps than $.20 stamps. How many stamps in all does she buy?
Answer by checkley77(12844) About Me  (Show Source):
You can put this solution on YOUR website!
.01*3X+.15(X+8)+.20X=5.00
.03X+.15X+1.2+.20X=5.00
.38X=5.00-1.20
.38X=3.80
X=3.80/.38
X=10 .20 CENT STANPS WERE PERDHASED.
3*10=30 .01 CENT STAMPS WERE PURCHASED.
10+8=18 .15 CENT STAMPS WERE PURCHASED.
10+30+18=58 A TOTAL OF 58 STAMPS WERE PURCHASED.
PROOF:
.01*30+.15*18+.20*10=5.00
.30+2.70+2.00=5.00
5.00=5.00