Which line passes through the point (3, 7)

The equation y=4x+b contains the point (3, 7). What is the value of b?

If a line has a slope of 2/3 and a y-intercept of (0,4) what is the equation in slope intercept form? **Try not to add spaces where they do not belong!

The equation y=2/3x+b passes through the point (6, 2) what is the value of b

What is the equation of a line with a slope of -1/5 and a y-intercept of 8? *Try not to add spaces where they do not belong.

What is the y-intercept of the equation with a slope of -1/5 and passes through the point (5,7)

What is the y-intercept of a line that has a slope of 5 and passes through the point (17, 122)?

There is some water in the tank, but more water needs to be added. When the valve is opened, water flows out of the tank at a constant rate of 5 gallons per minute. After the valve has been opened for 17 minutes, 122 gallons of water is in the tank. 

How many gallons of water were in the tank before the valve was opened?