Answer:
y=4.5
Step-by-step explanation:
You just have to remember that the equation of a horizontal line is a constant function, meaning that no matter what values are entered into the system, the answer for Y will always be the same. So in this case the function will be y=mx+b, since m or the slope in a horizontal line is 0 "x" will also be 0, so y=b, in this case as we can see in the point we are given b=4.5, so y=4.5
