Hey there!
Let's keep our goal in mind. We're looking fo a sum, which means a number plus a number, or the answer to that problem.
In order to simplify this, we need to use the distributive property which can be defined as:
a(b+c) = ab+ac
Now, we can use this forumula to express:
6(3+9) = 6(3) = 6(9) = 18 + 54 = 72
Hope this helps!