How do I Solve this pls help

Simplify 15(x - 4)(x -1)-3(x + 4)(x - 1) with steps

In the figure below, triangle rpq is similar to triangle rts. what is the distance between p and q? a. 24 b. 42 c.50 d. 54

You are standing next to a really big circular lake. you want to measure the diameter of the lake, but you don't want to have to swim across with a measuring tape! you decide to walk around the perimeter of the lake and measure its circumference, and find that it's 400\pi\text{ m}400? m. what is the diameter dd of the lake?