Alexis needs 280 screws to finish her deck. she bought 3 boxes of screws with 40 screws in a box. she had 168 screws. how many screws will she have left over when she finishes the deck?

8 screws

Step-by-step explanation:

1. You know that Alexis bought 3 boxes of screws with 40 screws in each box, then, to calculate the total number of screws she bought, you must multiply 3 boxes by 40 screws. Then:

2. Then, if she had 168 screws and she bought 120, now she has :

168 screws+120 screws=288 screws

 3. So to calculate the number of screws that she will have left over when she finishes the deck (which you can call ), you must subtract 288 screws and 280 screws. Therefore, you obtain the following result:

the correct answer is 45x

9×5=45 then add the x