Don is 21 years older than Betty. In six year Don will be twice as old as Betty. How old is each now?

Answer 1

If b is betty's age, then Don is b+21
In 5 years their ages will be b+6 and b+27
So,
b+27 = 2(b+6)
Solve for b, then you can get Don's age.

Answer 2

Betty is X years old.
Don is X+21 years old.

Six years from now:
Betty: X+6 years old.
Don: (X+21) + 6.

(X+21)+6 = 2(x+6).
X = ?
x+21 = ?

don

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