A and B complete a work in 6 days. A alone can do it in 10 days. If both together can do the work in how many days?
Choose the correct choice.
A) 3.75 days B) 3.78 days C) 3.25 days D) 3.15 days E) 2.75 days

Rationale: "1 / 6 + 1 / 10 = 8 / 30 = 4 / 15 15 / 4 = 3.75 days answer : a"
Answer: A