Question 775830

{{{x+y=20}}}.......eq.1
{{{x-y=4}}}.....eq.2
______________________ first find solutions that make both equations true

{{{x+y=20}}}.......eq.1
{{{x-y=4}}}.....eq.2
______________________...add eq.1 and eq.2

{{{x+y+x-y=20+4}}}

{{{2x+cross(y)-cross(y)=24}}}

{{{2x=24}}}

{{{x=24/2}}}

{{{highlight(x=12)}}}

now find {{{y}}}

{{{x+y=20}}}.......eq.1...plug in {{{x=12}}}

{{{12+y=20}}}

{{{y=20-12}}}

{{{highlight(y=8)}}}

to  verify that your solution is correct, go back to original equations and plug in values for {{{x}}} and {{{y}}}

{{{x+y=20}}}.......eq.1
{{{12+8=20}}}
{{{20=20}}}

{{{x-y=4}}}.....eq.2
{{{12-8=4}}}
{{{4=4}}}........since the left side of the equation is same as the right side in both eq.1 and eq.2 means your solution is correct