The diagram shows part of a regular polygon shaded in green. The interior angle is (28x+4)°.
The exterior angle is (5x+11)°.
How many sides does the polygon have?

Step-by-step explanation:

18.  8x-6-8=4+2x

8x-14=4+2x

-2x         -2x

6x-14=4

 +14     +14

6x=18

divide by 6= x=3

20. 24a-22=-4+24a

-24a                   -24a

-22=-4 there is no solution for this one since the a is 0

22. -1-7x+42+6x=36  add -1 and 42 together

41-7x+6x=36  add -7x+6x

41-x=36

-36    -36

5-x=0 add x to both sides

x       x

5=x

24. 6-3x=-6

+6           +6

12-3x=0

3x          3x

12=3x  divide by 3

4=x