Is (0,0) a solution of the graphed inequality?

Which expression is equivalent to -5(3x - 6/7)

See attachment below and find the equivalent of tan(∠qsr)

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?