Seller selling an apple for Rs.18, a Seller loses 1/6th of what it costs him. The CP of the apple is? Select:
A) 10
B) 12
C) 19
D) 18
E) 20

Rationale: "sp = 18 loss = cp 19 loss = cp − sp = cp − 18 ⇒ cp 19 = cp − 18 ⇒ 18 cp 19 = 18 ⇒ cp 19 = 1 ⇒ cp = 19 c"
Answer: C