Puzzlebomb is a monthly puzzle compendium. Issue 38 of Puzzlebomb, for February 2015, can be found here:

Puzzlebomb – Issue 38 – February 2015

The solutions to Issue 38 can be found here:

Puzzlebomb – Issue 38 – February 2015 – Solutions

Previous issues of Puzzlebomb, and their solutions, can be found here.

Is there an easy way to do this by hand? I can cast this as a linear algebra problem and compute it in Sage, but I’m curious if there is an easier way:

(Edited to remove the solution, but curious readers can execute the code to rediscover it – CP)