Answer:

Explanation:
Lesson: Substitution of systems of equation
In this question, we have
y + x = 3
and
y = 1.5 + 1
Clearly we are finding x, so we first have to get y alone on both sides.
y = 1.5 + 1 already has y alone. Therefore we focus on y + x = 3
y + x = 3
-x = -x
y = 3 - x
Now we can plug the two systems together because y is alone on both sides.
3 - x = 1.5 + 1
Combine like terms
3 - x = 2.5
Subtract 3 from both sides:
3 - x = 2.5
-3 = -3
-x = -0.5
Divide both sides by negative to get x alone:

x = 0.5