Step 1: Identify the complex number given in the question, which is z = -3 + 4i.
Step 2: Understand that a complex number is made up of a real part and an imaginary part. The format is a + bi, where 'a' is the real part and 'bi' is the imaginary part.
Step 3: In the complex number z = -3 + 4i, the real part is the number before the '+' sign, which is -3.
