Use BODMAS rule where start by opening brackets if your qstn involves brackets and then multiplication then addition then subtruction the ans you'll get will be the best ans ever. Multiply 3 by 50 u will get 150 then mltpy 3 by -x u will get -3x then your eqn will bee as follows 18+150-3x 27(50) then multply 27 and 50 it will be 1350then continue as i told in the begining with BODMAS rule where BO means brackets open ,Dmeans division ,M means multiplication ,A means addition and S means subtruction.this is the best way of solving it thank you.