Question 9783
Let x be the 1st number and y be the 2nd number.

Then:

{{{x = 2y}}} and
{{{(x-10) + (y-10) = 40}}}  Substiute x = 2y from the 1st equation.

{{{(2y-10) + (y-10) = 40}}}  Simplify and solve for y.

{{{3y -20 = 40}}}  Add 40 to both sides.

{{{3y = 60}}} Divide both sides by 3.

{{{y = 20}}} 

{{{x = 2y}}}

{{{x = 2(20)}}}

{{{x = 40}}}

Check:

{{{x = 2y}}}
{{{40 = 2(20)}}}

and:

{{{(x-10) + (y-10)= (40-10) + (20-10)}}} = {{{30 + 10 = 40}}}