Which is a stretch of an exponential decay function?

Solve 2x+y=3 x+y=5 in substitution method

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?

Which point-slope form equation represents a line that passes through (3,-2) with a slope of -4/5