4 is the commutative property of multiplication which states any terms being multiplied can "trade" placesm 5 is the associative property of multiplication that states you will still get the same answer when multiplying even if you switch what numbers are in the parenthesis. Both of those examples model moving the parenthesis. Gor the last question, you would simply plug in a 6 wherever you see an x.
(5(6) - 5)/8(6)
(30-5)/48
25/48
Hope this helps!