SOLUTION: Hi tutors, here's a challenging 5th grade word problem which I truly have no idea to work it out. William and Grace have $87. Grace and Siti have $115. William has 3/7 of Siti's

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Question 473291: Hi tutors, here's a challenging 5th grade word problem which I truly have no idea to work it out.
William and Grace have $87. Grace and Siti have $115. William has 3/7 of Siti's amount. How much money does Grace have at first?
Please help. Thank you.
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
William and Grace have $87. Grace and Siti have $115. William has 3/7 of Siti's amount. How much money does Grace have at first?
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W + G = 87
S + G = 115
W = (3/7)S
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I'm not sure how 5th graders solve these but
this is one way to do it.
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Substitute for W to get 2 equations in S and G
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(3/7)S + G = 87
S + G = 115
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Subtract and solve for "S":
(4/7)S = 28
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S = (7/4)28
S = 7*7
Siti has has $49
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Solve for "G":
S + G = 115
49 + G = 115
Grace has $66
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Solve for W:
W = (3/7)S
W = (3/7)49 = 3*7 = $21
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Cheers,
Stan H.
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