Identify the property that justifies each step asked about in the answer area below. Line 1: \text{Line 1: }\phantom{=}Line 1: =
(7x)(3y)\,\,(7x)(3y)(7x)(3y)
Line 2: \text{Line 2: }\phantom{=}Line 2: =
7⋅(x⋅3)⋅y\,\,7\cdot (x\cdot 3)\cdot y7⋅(x⋅3)⋅y
Line 3: \text{Line 3: }\phantom{=}Line 3: =
7⋅(3⋅x)⋅y\,\,7\cdot (3\cdot x)\cdot y7⋅(3⋅x)⋅y
Line 4: \text{Line 4: }\phantom{=}Line 4: =
(7⋅3)(x⋅y)\,\,(7\cdot 3)(x\cdot y)(7⋅3)(x⋅y)
Line 5: \text{Line 5: }\phantom{=}Line 5: =
21xy\,\,21xy21xy