I want to know what 3/4 of 5 is and i have no idea can you help?

What is the solution to this system of equations? y= 2x - 3.5 x - 2y = -14

Apackage of five erasers cost 0. $.39 at this rate how many how much would 60 erasers cost in dollars and cents

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?