You have to do PEMDAS. You skip the P because there are no parenthesis, you skip the E because there are no exponents, you start with the M because this means multiplication, so 3x6 is 18, so now you have 3-18+2. You then skip the D because there is no division, so you go to A which is addition, so 18+2 is 20. then you have 3-20 which is -17
