Help me pls i don't ge this

Find the greatest common factor of -30x 4 yz 3 and 75x 4 z 2.

What is not true about kl and mn? what is mn? (show )

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?