(23-12+21)/45 = 32/45

(109-(16+63))/250 = (109-79)/250 = 30/250 = 3/25

(57-(32-12))/190 = 37/190

(35+(15-9))/67 = 41/67

(42+8-29)/56 = 21/56

(203+40)/300 = 243/300