2x + y = 3
x = 2y - 1
solve for y in the first equation;
2x + y = 3
y = 3 - 2x
x = 2y - 1
x = 2(3 - 2x) - 1
x = -4x + 5
solve for x;
x = -4x + 5
x + 4x = 5
5x = 5
x = 1
solve for y;
y = 3 - 2x
y = 3 - 2(1)
y = 1
the answer is: x = 1, y = 1
hope this helps, God bless!