Can someone me with this 2 step eqaution

The answer is:  " 40 books " .

Explanation:

Let "x" equal the number of books that Jill started with.  Solve for "x" :

         x – (1/2)x  + 16 = 36 ;

1x – (1/2)) = (1/2)x ; 

(1/2)x + 16 = 36 ; 

Subtract "16" from EACH SIDE of the equation:

(1/2)x + 16 – 16 = 36 – 16  ; 

(1/2)x = 20 ; 

Multiply each side of the equation by "2" ; 

2*(1/2)x = 20 * 2 ; 

to get:  x = 40 . 

The answer is:  " 40 books " .

C. i believe it is (5×(-20))+(100×(0.7))