Supplementary means that they add up to 180 degrees. Those 2 angles should add up to 180 degrees. X is the missing angle and 42 degrees is the other angle. If both are added together they equal 180. To find x we can simply subtract 42 from 180 to get the x. 138 is x. The proof is that if 138 and 42 are added together they end up making 180 degrees. Therefore, the answer is 138
The answer is,

hope it helps.
Also, if you have any other questions like this, let me know. I'll help you. Have a good day!! Thank you.....
Answer:
yah if all your grades are A's and B's
Step-by-step explanation:
168
So you take the 144 divide 12(the dozen) so we could find how much 1 cost, it was 12. You added 2 more books so we add(12x2)+(144). That equals to 168
Hope this helps!
Answer:
(x-9)(x-8)
Step-by-step explanation: