Answer:
16) -7
17) 9
18) 5
19) 4
20) 10
21) -9
How?
X+139=132 by the alternate interior angle rule so solve and get -7
-1+14x=12x+17 by the alternate exterior angle rule so solve and get 9
21x+5= 23x-5 by the corresponding angles rule solve and get 5
20x+5+24x-1= 180 because when an angle is one a parallel line the sun of angle to the right or left of it is 180 solve and get 4
6x= 5x+10 by the corresponding angles rule solve and get 10
X+109+x+89= 180 because x+89 is equal to the angle that is too the right of x+109 by the alternate interior angle rule making the sum equal to 108. Solve and you get -9
That was a lot of math
Hope it helps :D