What is a polite and professional way to explain to my employer that since they’ve decided to cut our salary by 60%, that I’ll only be completing 40% of all assigned tasks from now on?

My employers have decided that since we're transitioning into a new company, they deserve raises since they'll be doing twice the amount of work. I work for a pretty small non-profit, having said that ALL OF US have had to do twice the amount of work we signed on for. I'm only contracted to work 40 hours of work a week, but recently I've had to work 60 hours a week and have even been called in for work ON MY DAYS OFF. But in spite of all of that, my employer has announced that the rest of us will be losing vision and dental benefits and be required to pay for health insurance out of pocket. Oh, and because we need to save money for the new company, thw rest of us will be getting pay cuts.