Detailed Instructions: Given a math problem with context and a question and 5 answer choices, the task is to provide the correct answer choice based on the problem. You must choose one of the given answer choices by letter: a, b, c, d, or e; anything else is invalid.
Q: Problem: a shopkeeper loses 15 %, if an article is sold for rs. 102. what should be the selling price of the article to gain 20 % ?
Options: a. rs. 146, b. rs. 144, c. rs. 129, d. rs. 123, e. rs. 128
A:
b