Which statement describes how to determine if a relation given in a table is a function? a. if none of the output values are repeated, the relation is a function. b. if none of the input values are repeated, the relation is a function. c. if any of the input values are equal to the output values, the relation is a function. d. if all the output values are paired with the same input value, the relation is a function.

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?