Question 981991
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D=daughter's age; F=father's age=D+25
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F+10yrs=2(D+10yrs) Substitute for F.
D+25yrs+10yrs=2D+20 yrs
D+35yrs=2D+20yrs
15yrs=D ANSWER 1: Daughter is 15 years old.
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F=D+25yrs=15yrs+25yrs=40yrs ANSWER 2: Father is 40 years old
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CHECK:
F+10yrs=2(D+10yrs)
40yrs+10yrs=2(15yrs+10yrs)
50yrs=2(26yrs)
50yrs=50yrs