What makes the statement true? 9^-2=?

(can someone explaining step by step? )

If f(x) = 4x – 3 and g(x) = 8x + 2, find each function value a.f[g(3)] b.g[f(5)] c.g{f[g(-4)]}

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?

If mary had 320 toy cars and she gave her friend 50 cars and then she gave her brother 72 more cars how much toy cars would mary have left ● explain with proper details