We can use the distribution method for this:
1/2r - 3 = 2(4 - 3/2r)
Multiply 2 by everything inside the parentheses:
1/2r - 3 = 8 - 3r.
Move variables to one side, and numbers to another:
1/2r + 3r = 8 + 3.
3 1/2r = 11.
7/2r = 11.
Divide by 7/2:
r = 22/7.
Not sure this is correct.