Question 343846
{{{M=3S}}}
In 15 years, she'll be M+15 and he'll be S+15
{{{M+15=2(S+15)}}}
{{{M+15=2S+30}}}
{{{M=2S+15}}}
Substitute from the first equation.
{{{3S=2S+15}}}
{{{highlight(S=15)}}}years old
Then from the first equation,
{{{M=3(15)}}}
{{{highlight(M=45)}}} years old