Question 638451: Dear Sir/Mame, any assistance in the following question will be gratefully taken.
'Marty buys some stamps. He buys 50 cent and 75 cent stamps to the value of $12.50. Altogether, he buys 21 stamps. How many of each type of stamp does he buy?
Thank You,
Kind Regards,
Sash Lack
Found 2 solutions by MathTherapy, lwsshak3:
Answer by MathTherapy(10552)   (Show Source):
You can put this solution on YOUR website!
Dear Sir/Mame, any assistance in the following question will be gratefully taken.
'Marty buys some stamps. He buys 50 cent and 75 cent stamps to the value of $12.50. Altogether, he buys 21 stamps. How many of each type of stamp does he buy?
Thank You,
Kind Regards,
Sash Lack
Let amount of 50c stamps purchased be F, and amount of 75c stamps, S
Then: F + S = 21 ----- eq (i)
Also, 50F + 75S = 1250 ----- eq (ii)
- 50F - 50S = - 1,050 ------ Multiplying eq (i) by - 50 ---- eq (iii)
25S = 200 ---- Adding eqs (iii) & (ii)
S, or amount of 75c stamps purchased =  , or 
F + 8 = 21 ----- Substituting 8 for S in eq (i)
F = 21 - 8
F, or amount of 50c stamps purchased = 
You can do the check, I'm sure!!
Send comments and “thank-yous” to “D” at MathMadEzy@aol.com
Answer by lwsshak3(11628)  (Show Source):
You can put this solution on YOUR website! 'Marty buys some stamps. He buys 50 cent and 75 cent stamps to the value of $12.50. Altogether, he buys 21 stamps. How many of each type of stamp does he buy?
**
let x=no. of 50 cent stamps Marty bought
21-x=no. of 75 cent stamps Marty bought
..
.50x+.75(21-x)=12.50
.50x+15.75-.75x=12.50
.25x=3.25
x=3.25/.25=13
21-x=8
no. of 50 cent stamps Marty bought=13
no. of 75 cent stamps Marty bought=8
|
|
|
