What is the domain of the following function?

Which is the most efficient first step to solve x in the equation 3.7x - 18 = -4.3x -34 a. add 3.7x to both sides of the equation. b. add 4.3x to both sides of the equation. c. subtract 18 from both sides of the equation. d. subtract 34 from both sides of the equation.

I'll give brainliest if you answer right : )

Find the midpoint m of z1=(8+5i) and z2=(12+3i)