8-2x<4 solve inequality

Solve - pv + 40 < 65 for v solve 7w - 3r = 15 for r

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?

Aiko jumped rope for 20 min and stopped at 8: 05 when did she start