Allen bought 20 stamps at the post office in 37cent and 20cent denominations. If the total cost of the stamps was $7.06, how many 37cent stamps did allen buy.
2007-08-19 11:04:46 · 9 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
let x = number of 37cent stamps
then 20-x = number of 20 cent stamps
0.37x + 0.2(20-x) = 7.06
0.37x + [(0.2x20)-0.2x] = 7.06
0.37x +(4 - 0.2x) = 7.06
0.37x - 0.2x +4 = 7.06
0.37x - 0.2x + 4 - 4 = 7.06 - 4
0.17x = 3.06
x = 3.06/0.17
x = 18
therefore Allen bought 18 37cent stamps
and 20-18 = 2 20cent stamps
2007-08-19 11:13:21 · answer #1 · answered by idiot detector 6 · 1⤊ 0⤋
OK this is what i did i started at $7.06 and i kept subtracting .37 till i came to a number divisible by 20.
so i got down to .40 with 18 stamps
so you will have 2 stamps @ .20, and 18 stamps @ .37
2007-08-19 18:17:34 · answer #2 · answered by kleino383 3 · 0⤊ 0⤋
let the number of 37cent stamps be x
let the number of 20 cent stamps be y
you have twenty stamps
x + y =20
the cost is 7.06
you have x number of stamps that cost .37 and y number of stamps that cost .20
.37x + .20y = 7.06
solve the system of equations
x + y + 20
subtract x from both sides
y = 20 -x
substitute (20-x) for y
37x + 20(20-x) =706
distribute
37x + 400 - 20x =706
combine like terms
17x = 306
divide both sides by 17
x = 18
Allen bought 18 stamps that cost 37cents.
2007-08-19 18:16:15 · answer #3 · answered by Chelsea 5 · 0⤊ 1⤋
19
2007-08-19 18:11:44 · answer #4 · answered by John 3 · 0⤊ 2⤋
.37x+.2y = 7.06
x+y = 20
Multiply by -.2
-.2(x+y) = -.2(20)
-.2x+-.2y = -4
-.2x-.2y = -4
.37x+.2y = 7.06
.17x = 3.06
Answer:
x = 18 stamps @ 37 cents
To verify answer:
18 * .37 + 2 * .2 = 7.06
2007-08-19 18:22:09 · answer #5 · answered by Chad K 2 · 0⤊ 0⤋
he bought 2 20-cent stamps and 18 37-cent stamps.
2007-08-19 18:13:37 · answer #6 · answered by Salsa Shark 4 · 1⤊ 1⤋
Hi Brad,
18 X.37 = 6.66
2 X .20 = .40
6.66 + .40 = 7.06
James :-)
2007-08-19 18:11:38 · answer #7 · answered by ? 3 · 0⤊ 0⤋
do an equation smart. uh duh!!!
37(x) + 27(y)= 7.06
2007-08-19 18:10:35 · answer #8 · answered by Anonymous · 0⤊ 3⤋
Why are we helping you? I know this a homework question so stop making people do your homework.
2007-08-19 18:10:01 · answer #9 · answered by hgkenneth800 3 · 0⤊ 3⤋