Evaluate the expression when x =19 and y =7

In which form is the following function written? y = - 2(x – 3)(x + 5)

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?

Sal is making bracelets for a fundraiser. he uses 6 inches of yarn per bracelet . how many bracelets can sal make with 5 feet of yarn