Can someone me i keep getting negative numbers for number 12

Consider, pls, this option:
(the sum of three angles must be 180°)
(60+x)+(x+85)+55=180;
2x=-20;
x= -10.
Note, that 60+85+55=200 > 180!
60+x=50° and x+85=75°.
If to check the sum.: 75+50+55=180°

than do 23.50 times 18 and then divide your answer by 100 than you will get x.