### A good answer might be:

Four bytes, for the single variable `a`.

# `main()`

Here is the code for `main()`, with some blanks. The rules for the subroutine prolog are copied from above.

    #  main()
    #  {
    #    int a;
    #    a = mysub( 6 );
    #    print( a );
    #  }

             .text
             .globl  main
    main:
                                      # prolog
             sub     $sp,$sp,4        #   1. Push return address
             sw      $ra,($sp)
             sub     $sp,$sp,4        #   2. Push caller's frame pointer
             sw      $fp,($sp)
                                      #   3. No S registers to push
             sub     ___,____,____    #   4. $fp = $sp - space_for_variables

             _____  $sp,$fp           #   5. $sp = $fp

                                      # subroutine call

             . . . .

                                      # return from subroutine

             . . . .

                                      # epilog
             jr      $ra              # return to OS

### QUESTION 9:

Fill in the blanks as the comments suggest.