Can some one me with the number line

Identify a1 and r for the geometric sequence an= -256(-1/4) n-1

The angle of a triangle are given as 6x,(x-3), and (3x+7). find x then find the measures of the angles

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?