(4 + i)(1 - 5i)
First, expand to get rid of parentheses.
[tex]4 - 20i + i + 5[/tex]
Second, gather the like terms which contain the same variables.
[tex](4+5) + (-20i + i)[/tex]
Third, add 4 + 5.
[tex]9 + (-20i + i)[/tex]
Fourth, subtract -20i + i.
[tex]9 - 19i[/tex]
Answer: 9 - 19i
