A movie rental company charges a monthly fixed membership fee of $13 plus $4 per movie that the user rents on that month. If M represents the number of movies that the user rents, and C represents the users total charge for the month, find the relationship between M and C.

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?