What is important here is the order of operations. There is a mnemonic that some people use to remember the order it is BEDMAS
- Brackets first
- Exponentiation next
- Division third
In your problem there are no brackets, no exponent ion and no divisions first perform the multiplication
3 - 6 + 4 3 = 3 - 6 + 12
Now the addition and then the subtraction.