What property is this in math 6+(4+x)=(6+4)+x

Ashopper bought a watermelon a pack of napkins and some paper plates in his state there was no tax on food the tax rate on non-food items is 5% the total for the three items he bought was 825 before tags and he paid $0.19 in taxes how much did the watermelon cost

Solve the inequality and graph 6j - 7 < 5

What is the measure of one interior angle of a pentagon