Find the distance from point p to rq

What is the effect on the graph of the function f(x)=x when f(x) is replaced with -f(x)+4

Can you me find the missing length. i attached an image.

The point a is at –2 and the point b is at 7. marissa would like to divide this line segment in a 4: 3 ratio, and she would like to use the formula x = (x2 – x1) + x1. what values should she substitute into the formula? a = a + b = x1 = x2 =