When writing an expression in expanded form, we just need to multiply what's outside the parentheses by everything that is inside the parentheses.
5a (6b + 12)
(5a * 6b) + (5a * 12)
30ab + 60a
And that is our answer.
5a (6b + 12) in expanded form is 30ab + 60a.
Hope that helped =)
