Help I know it's easy but I'm lost

He didn't add a placeholder or a 0 for multiplying the tens.

Step-by-step explanation:

Before moving onto the tens, you always have to put 0 under the ones value. In this case under 1 in 2871. Hope this helps!

5x+40

5(x + 8)

7x - 49

7(x - 7)

18x + 9

9(2x + 1)

15x - 10

5(3x - 2)

step-by-step explanation:

for number one all you have to do is factor 5 out of 5x + 40

for number 2 factor 7 out of 7x - 49

for number three factor 9 out of 18x + 9

for number four factor 5 out of 15x - 10

okay..i will pick 8!