You only have to answer 7,8 but if you want you can do 9 and 10

#7) x = 3

#8) x = 9

Step-by-step explanation:

# 7

Well AOB + BOC = AOC so...

4x - 1 + 2x + 15 = 8x + 8 (collect like terms)

6x + 14 = 8x + 8 (subtract 8 on each side)

6x + 6 = 8x (subtract 6x on both sides)

6 = 2x (divide by 2 on both sides)

3 = x

#8

COD + BOC = BOD so..

8x + 13 + 3x - 10 = 12x - 6 (collect like terms)

11x + 3 = 12x - 6 (add 6 on both sides)

11x + 9 = 12x (subtract 11x on both sides)

9 = x

Hope this helps!!

21.4 i did it already for s1

step-by-step explanation:

step-by-step explanation:

idk the answer i want to say 10 but then it would be equal so try 9 but then yeah so yeah we love edgen