(3/5) divided by 4
please help !!!

What two criteria are needed for triangles to be similar

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?

The random variable x is defined as the number marking the sector in which the arrow lands when the spinner in the diagram is spun once.