I need help pls and thanks

Which value of c would make he following expression completely factored? 8x+cy

Someone this asap for a group of students attends a basketball game. * the group buys x hot dogs at the concession stand for $2 each. * the group buys y drinks at the concession stand for $3 each. the group buys 29 items at the concession stand for a total of $70. how many hot dogs did the group buy?

Find the equation using the point (4,8)