Any thoughts im really confused on it

What is the effect on the graph of the parent function f(x) = x when f(x) is replaced with 3f(x)? a) shifts the line 3 units up b) shifts the line 3 units down c) increases the slope of the line by a factor of 3 d) decreases the slope of the line by a factor of 3

Solve 2x+y=3 x+y=5 in substitution method

If i have one apple and give you the apple, how many apples do i have?