Ana, Benito, Carlos and Diana are two couples who go shopping. At the end of the day, Carlos spent the same amount of money as his wife and Ana spent € 4 more than Benito. Among the four they spent € 85 in total and we know that each one spent an entire amount of euros.
What is Carlos's wife's name?
Carlos's wife is Ana.
The reasoning is as follows: From the problem data we know that one of the marriages spent an even amount and the other an odd amount. Carlos and his wife add an even amount and therefore Benito and his wife add an odd amount.
Ana cannot be Benito's wife since she spent € 4 more than what the couple as a whole would have spent an even amount. Therefore, Carlos's wife has to be Ana.