First of all if you have brackets then solve them first.
Then multiplication
Then division
Then addition
Then subtraction
These are the orders of the operations
PEMDAS
Parenthesis - Exponents - Multiplication - Division - Addition - Subtraction
42 ÷ (5 − 3) Solve in parenthesis first.
42 ÷ (2) No exponents. Skip this step.
42 ÷ (2) Skip multiplication. Divide.
= x
As the others stated, you should get 21 as a final solution.