Subtract 4a2 + 5b2 - 6c2 + 8 from 2a2 - 3b2 - 4c2 - 5.

(2a2 - 3b2 - 4c2 – 5) – (4a2 + 5b2 - 6c2 + 8)


= 2a2 - 3b2 - 4c2 – 5 - 4a2 - 5b2 + 6c2 – 8


= - 2a2 - 8b2 + 2c2 - 13


1