SOLUTION: Michelle is 21 years older than her brother Frank. Nine years from now, Michelle will be twice as old as Frank. How old is each at the present time?
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Question 1030858: Michelle is 21 years older than her brother Frank. Nine years from now, Michelle will be twice as old as Frank. How old is each at the present time? Found 2 solutions by fractalier, josmiceli:Answer by fractalier(6550) (Show Source):
You can put this solution on YOUR website! Call their ages NOW, m and f. Then we write
m = f + 21
Nine years from now,
m + 9 = 2(f + 9)
Substitute the first one into the second and get
f+21 + 9 = 2(f + 9)
f + 30 = 2f + 18
Now subtract 18 and subtract f and get
f + 12 = 2f
f = 12
Thus Michelle is 33.
You can put this solution on YOUR website! Let = Michelle's age now
Let = Frank's age now
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(1)
(2)
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Substitute (1) into (2)
(2)
(2)
(2)
(2)
and
(1)
(1)
(1)
Michelle is 33 and Frank is 12
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check:
(2)
(2)
(2)
(2)
OK
