Can someone help me with this De Morgan's Law question?

Question

. We have been learning about boolean algebra in school and can't figure out what to do for this question. Can anyone help explain the steps?

Answer 1

$$\overline{(\overline A+B)(A+\overline B)}=\overline{(\overline A+B)}+\overline{(A+\overline B)}=A\overline B+\overline AB$$

by De Morgan, and by the tip $$(A+B)(\overline A+\overline B)=A\overline A+ A\overline B+B\overline A+\overline B B=A\overline B+\overline AB.$$