Cost savings?

Hi! I had a quick question about this Preplounge case called "YodaPhone" - just about the calculation of benefits realized at the end of the case.

The client had additional benefits of $14.1. They had cost savings of 5.4M (original cost was 12M) --> Wouldn't that mean that the total benefits realized after costs = 14.1M - (12M - 5.4M) = 14.1M - 6.6M = 7.4M dollars realized after costs? The solution written on the case seems to calculate benefits realized as (total benefits - cost savings) instead. 

A bit confused about the logic of subtracting the amount of costs saved from the benefits realized as opposed to subtracting the actual costs. If anyone could let me know if/how I'm thinking about this the wrong way I'd be super grateful :)