Answer :
x+y=51
x-y=29
add equations
x+y=51
x-y=29 +
2x+0y=80
2x=80
divide 2
x=40
sub
x+y=51
40+y=51
y=11
they are 40 and 11
x-y=29
add equations
x+y=51
x-y=29 +
2x+0y=80
2x=80
divide 2
x=40
sub
x+y=51
40+y=51
y=11
they are 40 and 11