Question

find the complement of supplement of 120

Answer 1

 the supplementary of 120 =60
 the complementary of 60  =30

Therefore:

Ans=30

Answer 2

supplement of 120 is 60 (since , 180 - 120 = 60)
complement of supplement of 120 is nothing but complement of 60 .
Now , complement of 80 is 30 (since , 90 - 60 = 30)
So , complement of supplement of 120 is 30 .