Name the property that justifies each step.

Question

[(2 * 100) + (3 * 10)]+ [(1 * 100) + (5 * 10)]
= (2 * 100) + [(3 * 10)+ (1 * 100)] + (5 * 10)__________ property
= (2 * 100) + [(1 * 100)+ (3 * 10)] + (5 * 10)___________ property
= [(2 * 100) + (1 * 100)]+ [(3 * 10) + (5 * 10)]__________ property
= [(2 + 1) * 100]+ [(3 + 5) * 10] ____________property

I am confused on this, trying to figure out if commutative, distributive,etc.