Question 927665

Julia is twice as old as Helen:

{{{J=2H}}}...eq.1

 In {{{4}}} years, the sum of their ages will be {{{47}}}:

{{{(J+4)+(H+4)=47}}}....eq.2...substitute {{{2H}}} for {{{J }}} from eq.1

{{{2H+4+H+4=47}}}...solve for {{{H}}}

{{{3H+8=47}}}

{{{3H=47-8}}}

{{{3H=39}}}

{{{highlight(H=13)}}}

go back to eq.1 and find {{{J}}}

{{{J=2H}}}...eq.1

{{{J=2*13}}}

{{{highlight(J=26)}}}

so, let's check the answer:

in {{{4}}} years {{{J=30}}} and {{{H=17}}}, then their sum is {{{30+17=47}}}