Need to complete this for my senior year but I haven't been paying much attention to class this last quarter. If I could get some examples on how the Pn formula works I would appreciate it so much. Very worried about this

3x + 4y = 5 x- 3y = -7 solve by substitution

Which of the following will form the composite function?

Talia grouped the terms and factored out the gcf of the groups of the polynomial 15x2 – 3x – 20x + 4. her work is shown below. (15x2 – 3x) + (–20x + 4) 3x(5x – 1) + 4(–5x + 1) talia noticed that she does not have a common factor. what should she do?