Question 1168465
On Monday, five friends: Jamie, Susie, Sissy, Sandy, and Tiffany all put their money together for a United Way donation.
 Together they gave fifteen dollars and nine cents.
 Sissy gave twice as much as Susie. Susie gave ten cents more than twice as much as Sandy. Tiffany gave thirty cents less than Sandy while Jamie gave seventy-five cents less than four times what Sandy put in.
How much money did each person contribute?
:
let the 5 friends be a, b, c, d & e
write an equation for each statement
:
"Together they gave fifteen dollars and nine cents."
a + b + c + d + e = 15.09
" Sissy gave twice as much as Susie."
c = 2b
"Susie gave ten cents more than twice as much as Sandy."
b = 2d+.10
 "Tiffany gave thirty cents less than Sandy"
e = d - 30
"while Jamie gave seventy-five cents less than four times what Sandy put in."
a = 4d - .75
:
All the variables are in terms of d except c = 2b, we know b = 2d+.10
therefore
c = 2(2d+.10)
c = 4d + .20
:
substitute in the first equation for: a + b + c + d + e = 15.09
(4d-.75) + (2d+.10) + (4d+.20) + d + (d-.30) = 15.09
combine like terms
4d + 2d + 4d + d + d -.75 + .10 + .20 -.30 = 15.09
12d - .75 = 15.09
12 = 15.09 + .75
12d = 15.84
d = 15.84/12
d = 1.32
then
a = 4(1.32)-.75 = 4.53
b = 2(1.32)+.10 = 2.74
c = 4(1.32)+.20 = 5.48 
d - 1.32
e = 1.32 - .30 = 1.02
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Check total: $15.09
: 
We can then say
Jamie gave 4.53
Suzy gave  2.74
Sissie gave 5.48
Sandy gave 1.32
Tiffany gave 1.02
:
They could have all gave $3 plus a few pennies. but there is no fun in that, is there. Hope this helps you understand math a little better.  CK