54 x 120575957 divided by 12

The price of an item has been reduced by 30%. the original price was $30. what is the price of the item now ?

Sketch one cycle if the cosine function y=2cos2theta

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?