Using the substitution method.
2x + y = 3
x = 2y -1 Since x has been isolated already plug it into Equation 1
2(2y - 1) + y = 3 Solve for y.
4y - 2 + y = 3
+2 +2 Combine like terms and isolate y.
4y + y = 5
5y = 5 Isolate y by dividing both sides by 5
5y/5 = 5/5
y = 1
With y solved, solve either system for x.
x = 2(1) - 1
x = 2-1
x = 1
Solution is (1,1)