You can rationalize the denominator by multiplying the denominator by its conjugate. The conjugate of a complex number is formed by changing the sign between the two terms. However, if you multiply the denominator by something, you must multiply the numerator by that same thing so as not to change the value of the fraction. So:
For the numerator, just distribute the 4 across the two terms of the complex number. For the denominator, recall that the product of conjugates is the difference of two squares and that
