The K M Links Game - November 2024 Week...
Quizzes & Puzzles3 mins ago
Sharon is twice as old as Graham was when Sharon was as old as Graham is now.
If Graham is 24, how old is Sharon?
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For more on marking an answer as the "Best Answer", please visit our FAQ.It more difficult than it sounds. This is how I worked it out:
(1) Sh is twice as old as Gr was when Sh was as old as Gr is now
(2) Gr = 24
put (2) into (1) and you get
(3) Sh is twice as old as Gr was when Sh was 24
Let a = Sh now
Let b = Gr now
Let c = Sh then
Let d = Gr then
Therefore
(4) "Sh was as old as Gr is now" means b = c
(5) "Sh is twice as old as Gr was" means a = 2d
(6) constant age difference means that a - b = c - d
(7) Gr is now 24 means that b = c = 24
put (4) into (6) and you get
(8) a - b = b - d
put (5) into (8) and you get
(9) 2d - b = b - d
add d to both sides:
(10) 3d - b = b
add b to both sides:
(11) 3d = 2b
we know that b = 24, so:
3d = 48
d = 16
but b = c so therefore c = 24
constant age difference means that a = 32
So Shirley and Graham are now 32 and 24;
when Shirley was 24 they were 24 and 16.
QED