x+y=38; x-y=26-x
x + y = 38
x - y = 26 - x
x + x - y = 26
2 x - y = 26
x - y = 26 - x
is equivalent to :
2 x - y = 26
Your system is :
x + y = 38
2 x - y = 26
Using Substitution Method.
Expressing y as a function of x (from the first equation)
x + y = 38
y = 38 - x
Substituting this expression into the second equation:
2 x - y = 26
2 x - ( 38 - x ) = 26
2 x - 38 + x = 26
2 x + x = 26 + 38
3 x = 64 Divide both sides by3
x = 64 / 3
y = 38 - x
y = 38 * 3 / 3 - 64 / 3
y = 114 / 3 - 64 / 3
y = 50 / 3