Can someone me i don’t understand this

5x² + 9x + 3 - (6x² - 3x) =

= 5x² + 9x + 3 - 6x²+ 3x =

= (5x² - 6x²) + (9x + 3x) + 3 =

= -x² + 12x + 3

D.  -x^2 + 12x + 3.

Step-by-step explanation:

5x^2 + 9x + 3 -  (6x^2 - 3x)

First distribute the negative over the parentheses:

= 5x^2 + 9x + 3 - 6x^2 + 3x

Bring like terms together, then simplify:

= 5x^2 - 6x^2 + 9x + 3x + 3

= -x^2 + 12x + 3.

In this sample, are the events "female" and "prefers chocolate" mutually exclusive?  NO

P(female OR prefers chocolate)= 0.8