1. Use the FOIL method: (a+b)(c+d)=ac+ad+bc+bd(a+b)(c+d)=ac+ad+bc+bd(a+b)(c+d)=ac+ad+bc+bd
a^2b^2+8ab−9ab−72
2. Collect the like terms
a^2b^2+(8ab−9ab)−72
3. Simplify
a^2b^2-ab-72
Hope this helps
