90+x+72+30 = 180. If you add 90+72+30, you get 192. But to get 180 you have to subtract 12. 90+(-12)+72+30 =180 if x is -12
72 + 72 = 144
1 + 30 + 2 + 3 + 5 + 6 + 10 + 15 = 72
30 + 42 = 72
180+72=252
90+x+72+30 = 180. If you add 90+72+30, you get 192. But to get 180 you have to subtract 12. 90+(-12)+72+30 =180 if x is -12
72 + 72 = 144
1 + 30 + 2 + 3 + 5 + 6 + 10 + 15 = 72
30 + 42 = 72
49 + 72 + 68 = 189
180+72=252
You would formulate this problem X/100 * 150 = 72 and solve for X.
20 + 12 + 32 + 20 + 30 + 72 = 186
72 !
72
132
117