A ratio between two numbers is 5:4 and their L.C.M. is 80. The first number is
Select the correct option:  A) 60  B) 45  C) 20  D) 15  E) None
Sol.   Let the required numbers be 5x and 4x. Then, their L.C.M. is 20x.   ∴ 20x = 80⇔ x = 4. Hence, the first number is 20.   Answer 20
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A ratio between two numbers is 5:4 and their L.C.M. is 80. The first number is