Question 714560
{{{3x + 5y = -48}}}
{{{4x - 10y = -24}}}

Divide both sides of the lower equation by 2, so the factor of y becomes opposite to the factor of y in the upper equation.
{{{(4x - 10y)/2 = (-24)/2}}}
{{{2x - 5y = -12}}}
Since they are now the opposite of each other they disappear when you add them.

Examples:
{{{ -2y + 2y = 0}}}
{{{ 123y - 123y = 0}}}

So when you add the equations together you get this:

{{{3x + 2x + 5y - 5y = -48 - 12}}}

{{{5x = -60}}}
{{{x = -30}}}