A scale reads 100N when a pice of aluminum is hanging from it. What does it read when it is lowered so that the
aluminum is submerged in water? Book shows answer as Scale = 63.0 N how do I get to this answer.

Are you still having problems with this, given the reponses given to your other post? See: https://www.askmehelpdesk.com/math-sciences/help-639202.html