Concept:A custom operation is defined by a formula. Replace the variables with given numbers and simplify.Explanation:Given: A # B = (A + B) ÷ (A − B)Substitute A = 10 and B = 5.First, add: 10 + 5 = 15.Then, subtract: 10 − 5 = 5.Now divide: 15 ÷ 5 = 3.Answer:3 (Option B)