Madison measured 2 line segments. The first line segment is 20 cm long. The second line segment is 400 mm long. How long are the two line segments together?

What is the slope of a line that is perpendicular to y = 3x + 1

Idon’t understand this.. will someone ? will mark brainliest along with 20 points.

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?