Answer:
+35 per month
Step-by-step explanation:
Commutative says you can add or multiply in any order
basically goes like this
a+b=b+a or
ab=ba
so what we need is something where the order change, nothing else
first one: (4+3)+x=(3+4)+x, the order changed, correct
2nd
ab=ba, this is not addition
3rd
r+(s+t)=(r+s)+t this is associative property
4th
n+0=n
this is zero addition property
answer is first one
40(60/100) 4(6/10) =24/10 = 2.4