Question

I’m 25. If we add my sister’s age to mine, we found our father’s age. In 2 years, my father will be twice older than my sister. How old are my sister and father?

Answer 1

S=sister's age.

25+S is father's age. In two year's time sister will be S+2 years old and father will be 27+S years old.

27+S=2(S+2),

27+S=2S+4,

23=S (sister's age now), 25+23=48 (father's age now).

Answer 2

25+x=y
y+2=2x

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(25+x)+2=2x

x=27

if x=27, y=52