The answer is
Step-by-step explanation:
First we must follow the order of operation: Please, Excuse, My, Dear, Aunt, Sally; Paranthesis, Exponents, Multiplication, Division, Addition, and Subtration.
First it says to look for parenthesis, which there are; so we do that first;.
3(7x) -2 (4 - x)
 ^
21x - 2 (4 - x)
        ^
 21x - 2 times 4 (btw, we took x away because 4 - x)
        ^ (now we do multiplcation)
   21x - 8 Â
      ^
      13
answer is 13 + 2x
     Â