Someone help me please

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

1mile equals approximately 1.6 kilometers. which best approximates the number of miles in 6 kilometers?

With alll of except for the 2 that i did already