Question

A stamp collector bought 160 stamps for $25.00. The purchase included 5¢ stamps, 15¢ stamps, and 25¢ stamps. The number of 15¢ stamps is three times the number of 5¢ stamps. How many of each type of stamp was purchased?

Answer 1

I found 25 cents and 15 cents, but i cant seem to find 5 cents

Answer 2

how did you solve this for 25c and 15c?

Answer 3

160-4x = 160 -(4*30) = 40 for 25 cents
160 - 3x = 160 - (3*30) = 90 for 15 cents

Answer 4

how did you get 4x?

Answer 5

let 5cents stamps to be x and so for 15cents and 25 cents as y ,z respectively

Answer 6

i addded 3x + x

Answer 7

now 15 cts stamps are thrice the time of 5 cts
=> y=3x;

Answer 8

now again total no. stamps is 160
hence x + y + z =160
also total amount is 25 $
so 5x+15y+25z=25

Answer 9

solve all three equetions for solutions

Answer 10

okaay

Answer 11

would i plug in 25 for x y and z?

Answer 12

no x for 5 , y for 15 and 25 for z

Answer 13

from 1st eq. y=3x
puting in 2nd and 3rd we have
x+3x+z=160 => 4x + z = 160 ............1
and 5x + 15*3x + 25 z = 2500 ..........2 (since in doller not in cents)
=> 50x + 25z =2500 or 2x + z = 100 .........2

Answer 14

wouldnt it be .5 .15 .25?

Answer 15

now from new equation 4x +z =160
and 2x + z =100
2(100-z) + z = 160
200 -2z +z =160
=> z=40

put in 2x +z = 100 =>
x=(100-40 ) / 2
x = 30

and y = 3*30 as 3x
y=90 hence solved as
30 stamp for 5 c
40 stamps for 25 c
and 90 stamps for 15 c

Answer 16

yes .5 .25 .15 for 25
or 5 25 15 for 2500 both are same

Answer 17

oh okay, thank you :)

Answer 18

it s okay ;)