You have to subtract 3x + 18 from 5x - 12:
=> 5x - 12 - ( 3x + 18) = 5x - 12 - 3x - 18 = 5x - 3x - 12 - 18 = 2x - 30
The first step was to apply distributive property to supress the parenthesis, after that the terms were arranged and the like terms combined.
2x - 30
be more specific bud
Step-by-step explanation: