Identify properties used in each step in rewriting the polynomial expression below: (x + 5) + 3(a + (6x)y) step 1: (5 + x)+3(a + (6x)y) step 2: 5 + (x + 3(a + (6x)y) step 3: 5 + (x + 3a + (18x)y) step 4: 5 + (x + 3a +18xy)

In step 1, the commutative property of addition is used since x + 5 is just equal to 5 + x
In step 2, the associative property of addition is used since x is grouped to the last term.
In step 3, the distributive property of multiplication is used since 3 is multiplied to the terms inside the parenthesis. 
In step 4, multiplication is done.