I'm not exactly a professional on this topic, but you can look if this may be the answer you are looking for in the image below.
(5.992, 0) is your answer.
I think -23/4 hope it helps
Answer should be 60! hope this helps :)
Total people=180
discount received people=25%+10%=35%
People who did not receive discount=100-35%=65%
65%of 180=65×180/100=117
So 117 people did not receive discount