Step-by-step explanation:
This is a linear equation in slope intercept form which is

where m is the slope and b is the y intercept.
The equation

Has a slope of -1/3 so this means that the slope will be decreasing. A negative linear equation increases as we go left. and decreases as we go right. The y intercept is 2. So this means the graph must pass through (0,2) and when x=0, y must be 2.
In other words, look for a line that the y values increase as we go left and decrease we go right. Also look for a point (0,2) and make sure the graph pass through it.
50 because 80+50+x=180 (inside triangle) x=130 180-130= 50 (angle outside triangle)
The diver will make 12 stops before reaching the surface.
To solve for x
x+7y=-4
x=-4-7y