Question 394023
So it depends which variable you want to use, ill use x in this case

take the equation x+y=4 and isolate the x so its
x = (4 - y)

then in the other equation, replace x with (4-y)

y = 2(4 - y) + 1

Now you have only one variable :D

y = 8 - 2y + 1

combine like terms, yada yada

3y = 9
y = 3


Now just plug the number in to the original equation to get X 

x + 3 = 4
X = 1


the answer would be (1,3)