Question 857813
What sort of parent names their child Dimpy?
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Let M = Dimpy, and D = Dudley
5M = D - 1 [five times Dimpy's age is the same as Dudley's age decreased by 1]
D = 25 + M [Dudley was 25 years old when his daughter Dimpy was born]
Substitute the known value of D from the second equation into the first.
5M = (25+M) - 1
5M = M + 24
Subtract M from each side
4M = 24
Divide each side by 4
M = 6
If Dimpy is 6, then Dumpy...er, Dudley is 31.
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Let's plug it into the second equation to prove.
"five times Dimpy's age is the same as Dudley's age decreased by 1"
5 * 6 = 31 - 1
30 = 30
Success!