06. 1 0 1/2 π
07. commutativity (+), commutativity (*), associativity (+), associativity (*), distributivity of * over +
08. 3x+3y 8a-8b 28y-14x 3ab+3ac-6ad
09. 17/30 9/20 3 1/36
11. 100 -12 6/24 2 -1 1
13. 109.9884 48.36 30.24 42313990.36