All of the counting numbers (only count positive) no fractions or decimals

Which addition property is being illustrated below? (type commutative or associative) (6 + 7) + 1 = 6 + (7 + 1)

Scarlet bought three pairs of sunglasses and two shirts for $81 and paula bought one pair of sunglasses and five shirts for $105 what is the cost of one pair of sunglasses and one shirt?

Bradley hikes 12 miles in 3 hours. in relation to bradley’s hike, which statement describes the expression