Question 1071658
Ten years ago,
{{{M-10=6(D-10)}}}
In ten years,
{{{M+10=2(D+10)}}}
From the first equation,
{{{M-10=6D-60}}}
1.{{{M-6D=-50}}}
From the second,
{{{M+10=2D+20}}}
2.{{{M-2D=10}}}
Subtracting 1 from 2,
{{{M-2D-M+6D=10-(-50)}}}
{{{4D=60}}}
{{{D=15}}}
So then,
{{{M-2(15)=10}}}
{{{M-30=10}}}
{{{M=40}}}