Posted by **Robbie** on Tuesday, March 29, 2011 at 10:14am.

plz explain how to do this in detail:

using only 39 cent and 24 cent stamps, charlie put $7.14 postage on a package he mailed to his sister. if he used twice as many 39 cent stamps as 42 cent stampsp, how many 24 cent stamps did he use??

- algebra 1 -
**Jai**, Tuesday, March 29, 2011 at 10:39am
first represent the unknowns using variables:

let x = number of 24-cent stamps used

let 2x = number of 39-cent stamps used (according to the second statement)

since the total is 7.14 dollars,

0.24x + 0.39(2x) = 7.14

now we solve for x:

0.24x + 0.78x = 7.14

1.02x = 7.14

x = 7 (number of 24-cent stamps used)

hope this helps~ :)

- algebra 1 -
**jose**, Tuesday, March 29, 2011 at 11:31am
Triple a number plus 7 results in 16. What is the number?

- for the 2nd question -
**Jai**, Tuesday, March 29, 2011 at 11:39am
let x = number

according to the first statement, we multiply the number by three, then we add 7 to get 16,, writing in equation:

3x + 7 = 16

now solve for x,, first we transpose the 7 on the other side of equation,, to do this we change its sign from positive to negative:

3x = 16 - 7

3x = 9

to get x alone, we divide both side of equation by 3:

(3x)/3 = 9/3

x = 3

hope this helps~ :)

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