Step 3: Determine what operations to be used. (1) To obtain LKT, LKT = 10 students who visited the THREE tourist spots (2) To obtain TK, TK = 15 - LKT TK = 15 - 10 TK = 5 students who went to Tupi and Koronadal Cityminus LKT by substitution students who went to Tupi and Koronadal City only​