ANSWER
![y = 4](https://img.qammunity.org/2020/formulas/mathematics/middle-school/djptzgndq6np6ccseh6ftt43z1009forvo.png)
EXPLANATION
Since the y-coordinate of all the points on a given line is 4, it means the line is parallel to the x-axis and has slope, zero.
The equation of all lines parallel to the x-axis that pass through:
![(x_1,y_1)](https://img.qammunity.org/2020/formulas/mathematics/high-school/19r3d7du1thfjdcyjucmq84asmb0fngoya.png)
is
![y = y_1](https://img.qammunity.org/2020/formulas/mathematics/high-school/9j32qzb5topehmxsznlok3svhze2a3tbmo.png)
Since the line passes through
![(x_1,4)](https://img.qammunity.org/2020/formulas/mathematics/high-school/ggapx0d48f6ar8pzm1gt8g25m4jedvptm6.png)
or
(0,4)
Its equation is:
![y = 4](https://img.qammunity.org/2020/formulas/mathematics/middle-school/djptzgndq6np6ccseh6ftt43z1009forvo.png)
See attachment for graph.