Here is a set of basic questions producing integer or string outputs. Answer them and format the result precisely with the JSON instructions provided:

Question 0 (Question id: q_ZO4M):
Your job is to return the last character of a string as a string. For example, the last char of "hello" is "o". Return the last character of the following string: "economy"

Question 1 (Question id: q_5NC23):
Calculate ( 4 - 1 ).

Question 2 (Question id: q_ZuBMrWn):
Your job is to return the last character of a string as a string. For example, the last char of "hello" is "o". Return the last character of the following string: "fairly"

Question 3 (Question id: q_BKbdm0):
Solve for k: 15*k + 2 = 137 Respond with an integer.

Question 4 (Question id: q_OKefJq):
How many times does the letter "r" appear in the text: "and terrestrial"? Respond with an integer.



Return a JSON with each question id as a key.

Each key’s value must be an object holding an 'answer' field.
If the response to a question is an integer that is even, add the field 'additional_answer_info' containing 'half_answer' (answer ÷ 2) and 'double_answer' (answer × 2).
If the question asks for the last character of a string, add an 'original_string' field containing the source string.

Now provide the result JSON using the described format.

{"ground_truth": {"q_ZO4M": {"answer": "y", "original_string": "economy"}, "q_5NC23": {"answer": 3}, "q_ZuBMrWn": {"answer": "y", "original_string": "fairly"}, "q_BKbdm0": {"answer": 9}, "q_OKefJq": {"answer": 3}}}