Brooke has 15 mate problems 5 social studies problems and 9 science problems use mental math to determine how many problems she has for homework tell wish property you used

In your head, you should be able to add 15 and 5.  The answer is 20.  You should also be able to work out 20 + 9.  The answer is 29.  The trick to doing well at these types of questions is finding the quickest and easiest method of working them out.  It will come with practice :)