SOLUTION: Sandy is 7 years younger than Mandy, in 4 years time sandy will be half Mandy's age. What are their ages presently

Question 1069073: Sandy is 7 years younger than Mandy, in 4 years time sandy will be half Mandy's age. What are their ages presently
Found 2 solutions by ankor@dixie-net.com, ikleyn:
Answer by ankor@dixie-net.com(22740)   (Show Source): You can put this solution on YOUR website!
Sandy is 7 years younger than Mandy,
s = m - 7
in 4 years time sandy will be half Mandy's age.
s + 4 = (m + 4)
get rid of the fraction, multiply both sides by 2
2(s + 4) = m + 4
2s + 8 = m + 4
2s = m + 4 - 8
2s = m - 4
replace s with (m-7), from the first statement
2(m-7) = m - 4
2m - 14 = m - 4
2m - m = -4 + 14
m = 10 yrs is Mandy's age
:
What are their ages presently
I'll let you find Sandy's age, check the solutions in the 2nd statement
Answer by ikleyn(52792)   (Show Source): You can put this solution on YOUR website!
.
Sandy is 7 years younger than Mandy, in 4 years time sandy will be half Mandy's age. What are their ages presently
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Let S be the Sandy's present age, M be that of Mandy. S = M -7, (1) S + 4 = . (2) Multiply eq(2) by 2 (both sides). You will get the system in this form S = M -7, (1') 2S + 8 = M+4. (2') Substitute the expression (1') for S into (2'), replacing S. You will get 2*(M-7) + 8 = M+4 ---> 2M - 14 + 8 = M + 4 ---> M = 14 - 8 + 4 = 10. Answer. Mandy's present age is 10 years. Sandy's present age is 10-7 = 3 yeras.

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    - Really intricate age word problem
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The referred lessons are the part of this online textbook under the topic "Age word problems".

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