To solve the expression we must use order of operations following the memotecnic rule PEDMAS that states the order of operations. First solve parenthesis, then exponents, then divisions and multiplications from left to right and finally additions and subtractions from left to right . Following this rule we have:
30-2(7+2)-1
First parenthesis
30-2*(9)-1
There are no exponents. There are no divisions so we do multiplications first
30 -18 -1
There are no additions we only do the remaining subtractiosn form left to right
