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Friday, August 18 2017 @ 07:38 AM CDT
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 Maths Question 3
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By: shirley wee (offline)  Sunday, April 07 2013 @ 07:11 AM CDT (Read 668 times)  
shirley wee

Hi everybody! I'm stuck with this maths question. May you help me? Please show your working clearly.

Qn 1. Jacky, Kim and Leon shared the cost of a present for their mother. Kim and Leon paid 55% of the total cost. Jack and Leon paid 70% of the total cost. Leon paid $7 less than Kim. What was the total cost of the present?

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By: echeewh (offline)  Sunday, April 07 2013 @ 01:18 PM CDT  
echeewh

Hey Shirley,

Following pls find my worked solution:

*** - for alignment purpose


K+L: 55%
J: 45%

J : K+L ** Total
45 : 55
9 : 11 **** 20 -- (1)

J+L: 70%
K: 30%

K : J+L ** Total
30 : 70
3 : 7 ***** 10 -- (2)

K - L = $7

Comparing the above ratios (1), (2), and applying <Unchanged Total> concept {since J,K,L shared the cost of a present}, we multiply (2) 2x.

J : K+L
9 : 11

K : J+L
6 : 14

Hence, J = 9u; K = 6u; L = 20u - 15u = 5u

Given K - L = $7, we have ...

6u - 5u = 7
1u --> 7

Total cost of present = 20u --> 20 × 7 = $140

========

Trust this helps.

Do let me know again if this is different from your Answerkey or if theres further clarification.

Cheers,
Edward

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