Help please! if you know the problem.

x = ___ units

Solve 3x-18=2y and 5x-6y=6 by elimination show work

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?

Jimmy can run 3.5 miles in 20 minutes. how far can ne run in one hour and ten minutes?