To determine this you need to determine what is divide in both 18 and 8. The only number that can divide in both numbers is 2. Which means they have a common factor/number. And then you continue looking at the expression and see what other numbers or letters are common. The only common thing besides the number is a and b since it’s found in both. There is no c in 18ab. Hope this makes sense
Please mark as a brainliest (crown) above my comment. Would be much appreciated
