The expression 12(x + 4) represents the total cost of cds mei bought in april and may at $12 each. which property is applied to write the equivalent expression 12x + 48?
a- associative property of addition
b- associative property of multiplication
c- commutative property of multiplication
d- distributive property

The students at jefferson middle school are raising money for a charity by selling t-shirts and hats. the number of t-shirts sold was 3 times the number of hats. the profit was $5 for each t-shirt sold and $2.50 for each hat sold. the students raised $840 for the charity. they used the system below to analyze their success and found the solution to be (144, 48). 5x+2.50y=840 x=3y how much did they earn from t-shirt sales?