15. the operation * is defined on the set r
a
+b
– 1 for
of real numbers by a*b =
all a, ber.
(a) is r closed under* ?
(b) is the operation * commutative
in r?
(c) is the operation * associative in
r?

Problem melissa is her dad build a walkway in their backyard. the walkway will be 54 feet long and 1.5 feet wide. the local hardware store sells tiles which are 1.5 by 1.5 feet and come in boxes of 12. how many boxes of tiles do they need?

Justin has 750 more than eva and eva has 12 less than justin together they have a total of 63 how much money did

Describe the symmetry of the figure. identify lines of symmetry, if any. find the angle and the order of any rotational symmetry.