Please help if right I get the brainalist answer

Consider the function f(x)=-5x+3 what is f(-2)

What is the lcm of 16 and 40 ? 24 and 40 ?

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?