Question 369177
3 times one number (3x)  minus a second (-y) is 8 (=8).  SO 3x-y=8.
sum of numbers (x+y) is 12 (=12). SO x+y=12.
{{{3x-y=8}}}
{{{x+y=12}}} Solve this equation for y to get {{{y=12-x}}} Then you will plug this new value of y into the first equation and solve for x.

{{{3x-(12-x)=8}}}
{{{3x-12+x=8}}}
{{{4x-12=8}}}
{{{4x=20}}}
{{{x=5}}}  Then plug this value for x back into one of the equations to find y.

{{{x+y=12}}}
{{{(5)+y=12}}}
{{{y=7}}}
So the two numbers are 5 and 7.