SOLUTION: Hi Sally spent 3/7 of her money while Andrew spent $36. When his father gave him $20 andrew had 1/4 of the amount of money Sally had left. If they had $320 at first how much money

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Question 1206818: Hi
Sally spent 3/7 of her money while Andrew spent $36. When his father gave him $20 andrew had 1/4 of the amount of money Sally had left. If they had $320 at first how much money did Sally have left.
Thanks
Found 2 solutions by mananth, josgarithmetic:
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
Let Sally have $x
She spent 3x/7
She had balance 4x/7
Let Andrew have $y
Andrew spent 36
He had balance y-36
Father gave 20
So he had y-16
andrew had 1/4 of the amount of money Sally had left.

1/4(4x/7)= (y-16)
x/7 = y-16
x= 7y-112
They both had $320
x+y=320
7y-112+y= 320 ( substitute x)
8Y=432
y= 54
x+y=320
x= 320-54= 266
x=266
y=54
Sally had $266 and Andrew had $54
Sally,s balance
x- 3x/7
266 - (3/7) *266
266- 114= 152 (Sally,s balance)

152/4 = 38
1/4 of Sally,s balance =38
Andrew had 54
54-36+20=38

Answer by josgarithmetic(39630) About Me  (Show Source):
You can put this solution on YOUR website!
PERSON       VARIABLE        STEP 1          STEP 2
Sally           x             x-3x/7           4x/7
Andrew          y             y-36            y-36+20=y-16

After step 2, description gave
y-16=%281%2F4%29%284x%2F7%29
7y-112=x

Described initial total for both combined, $320.
x%2By=320

The system, system%28x=7y-112%2Cx%2By=320%29

Simple substitution,.....
system%28x=266%2Cand%2Cy=54%29
-but the question was,
"How much did Sally have left?"
-
%284%2F7%29266=highlight%28152%29-----------how much she had left