Hi There!
I believe the answer to the first box would be 9x. Then second box would then be 45. The first and second box would be 9x and 45 because there are 9 chairs in each row making the number of chairs total to 45 chairs. The third and final box would be x=5. The third box would equal 5 because when 9 is multiplied by 5, the answer of the equation equals 45.
I hope this helps!
