Chapter 2 Linear Equations and Functions - 2.4 Write Equations of Lines - 2.4 Exercises - Skill Practice - Page 103: 46

See below.

a) d) These both mean that the line is parallel to the x-axis, thus the equation is in the form $y=b$. Since $(3,4)$ is on the line, the equation is $y=4$. b) c) These both mean that the line is parallel to the y-axis, thus the equation is in the form $x=b$. Since $(3,4)$ is on the line, the equation is $x=3$.