12x - 3(x + 2)
First you must distribute the -3 to the numbers inside the parentheses, which would be x and 2...
12x + (-3*x) + (-3*2)
12x + (-3x) + (-6)
12x - 3x - 6
Combine like terms. This means the numbers with the same variables must be combined. In this case combine 12x and -3x
12x + (-3x) = 9x
D. 9x - 6
Hope this helped!
~Just a girl in love with Shawn Mendes