What equation does the graph show ?

What is the equation in point slope form of the line that passes through the point (-1, -3) and has a slope of 4? y-1=4(x-3) or y+3=4(x+1)

The depth of a lake at a certain point, wich is a function of the distance of that point from shore, is 30 feet.

Answer question above and explain each step : )