Final answer:
The expression simplifies to 3 using the Order of Operations, or PEMDAS, to execute multiplication, division, subtraction and then addition.
Step-by-step explanation:
First, you want to simplify the expression inside the { }. This involves doing multiplication and division before addition and subtraction, which is referred to as the Order of Operations or PEMDAS (Parentheses, Exponents, Multiplication and Division, Addition and Subtraction).
Step 1: Inside the brackets, subtract 9 from 6 to get -3. Multiply -3 by 3, which gives -9. Meanwhile, divide 12 by -2 which gets -6. Therefore, { 3( 6 - 9 ) + 12 ÷ ( - 2)} becomes { -9 -6 }, which simplifies to -15.
Step 2: Now we have -12 - { -15 }. Because subtracting a negative is the same as adding a positive, the equation simplifies to -12 + 15, which equals 3.
Learn more about Order of Operations