Part A
Looking at the graph
we have that
z1 ------> the coordinates are (3,5)
so
the standard form is z1=3+5i
z2 ------> the coordinates are (6,-3)
so
the standard form is z2=6-3i
Find out the distance between them
z2-z1=(6-3i)-(3+5i)
z2-z1=(6-3)+(-3i-5i)
z2-z1=3-8i
Find out the magnitude of the complex number (Applying the Pythagorean Theorem)

The distance between z1 and z2 is the square root of 73 units
Part B
Find out the conjugate of z2
we have
z2=6-3i
so
Remember that
You find the complex conjugate simply by changing the sign of the imaginary part of the complex number
therefore
The conjugate of z2 is (6+3i)
To find out geometrically change the sign of the y-coordinate (imaginary part) of the complex number (Reflect the given point over the x-axis)