how do you simplify this expression.

4 + √16-(4)(5) / 2
Simplify the numerator:
4 + √16 -20 = 4 +√-4
Now you have 4 + √-4 / 2
Rewrite the -4 as -1 *4
4 + √ -1*4 / 2
Rewrite √-1*4 as √-1 * √4
√-1 = i
Now you have 4 + i * √4 / 2
√4 = 2
Now you have 4 + i * 2 /2
Divide the numerator by the denominator to get the final answer: 2 + i