The given expression is :
[tex](-9x^2-2x)-(-9x^2-3x)[/tex]We will simplify the expression by using BODMAS rule :
B-Brackets
O-Of
D-Division
M-Multiplication
A-Addition
S-Subtraction
Since in the give expression we first open the brackets:
[tex](-9x^2-2x)-(-9x^2-3x)[/tex]