Answer :
Given
(b^2 + 13b - 9) - (6 -4b + 3b^2)
Expand
b^2 + 13b - 9 - 6 +4b - 3b^2
Rearrange
b^2 - 3b^2 + 4b + 13b - 9 - 6
simplifying
-2b^2 + 17b - 15
The first box is -2
The second is 17
The third box is -15
Given
(b^2 + 13b - 9) - (6 -4b + 3b^2)
Expand
b^2 + 13b - 9 - 6 +4b - 3b^2
Rearrange
b^2 - 3b^2 + 4b + 13b - 9 - 6
simplifying
-2b^2 + 17b - 15
The first box is -2
The second is 17
The third box is -15