Hi I'm Ashley. Here are some ways to do algebra, variables and expressions.When you have a sum or a difference, you take that first. Like,

 39 is less than the sum of 24 and 16.

Hi, this is Crater.  And I will tell you how to finish this problem.  39 is less than the sum of 24 and 16 right? Well that means the keywords would be less than and sum, right?  Then that would mean that it would be (24+16)-39=?. Than you and the #'s in parenthesis. Those #'s would be 24+16. Then you add them together. Which would be 40. If you had 39-(24+16) that would be wrong because you can't subtract 39-40. It has to be 40-39.So 40-39 is 1 and that's the answer!