The value of x is 19.
The value of y is 4.
x = 3 + 4y
x + y = 23
Because we have a value for x we can plug it directly into the second equation.
3 + 4y + y = 23
Subtract 3 from both sides.
4y + y = 20
Combine like terms.
5y = 20
Divide both sides by 5.
y = 4
Plug this value for x back into the original equation.
x = 3 + 4(4)
x = 3 + 16
x = 19