Question 982979
{{{x/4 + y/4 = 1}}}
{{{x/5 - y/5 = 12/5}}}
First step, get rid of the fractions.
Multiply each row by the denominator in the row.
1.{{{x+y=4}}}
2.{{{x-y=12}}}
Replace the second row by multiplying the previous second row by (-1) and adding to the first row.
{{{x+y-x+y=4-12}}}
{{{2y=-8}}}
3.{{{y=-4}}}
So that leaves you with
1.{{{x+y=4}}}
2.{{{y=-4}}}
Substituting,
{{{x-4=4}}}
{{{x=8}}}