Identify the property used in each step. 12.2 + 18.6 + -4.3 + (-18.6) 12.2 + -4.3 + 18.6 + (-18.6) = (property?) 12.2 + -4.3 + [18.6 + (-18.6)] = (property?) 12.2 + -4.3 + (0) = (property?) 12.2 + -4.3 7.9

Tommy buys a sweater that is on sale for 40% off the original price. the expression p -0.4p can be used to find the sale price of the sweater, where p is the original price of the sweater. if the original price of the sweater is 50, what is the sale price?