Question 334856
You're mixing up the present and future ages in the equations.
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I'll use F for the father's age, S for the son's.
Father's age is three years more than three times the 
son's age.
1.{{{F=3+3S}}}
After three years, the father will be F+3 and the son will be S+3.
{{{F+3=10+2(S+3)}}}
{{{F+3=10+2S+6}}}
{{{F+3=2S+16}}}
2.{{{F=2S+13}}}
Now since they're both equal to F set them equal to each other and solve for S.
{{{3+3S=2S+13}}}
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They using S, solve for F.