Please help me pleasee

Dylan is evaluation the expression 13+19+7+10 at one step in his work, dylan rewrites the equation as 13+7+19+10 which property of addition must dylan have used when he evaluated the expression?

Griffin ordered a pair of sneakers online. he had a $22 credit that he applied toward the purchase, and then he used a credit card to pay for the rest of the cost. if the shoes cost $58, how much did griffin charge to his credit card when he bought the sneakers?

Whats is the value of the variables ?