I need help graphing these problems on a coordinate plane
I need to hire a plumber. I have two friends that are recommending a plumber. One friend said for 3
hours of work the plumber charged $300. My other friend hired the same plumber and for 7 hours of work charged $500.
A water tank holding 200 gallons of water has sprung a leak. The leak releases 10 gallons of water
every hour.
for the plumber, you have two points: (3,300) and (7,500)
The slope of the line joining these two points is (500-300)/(7-3) = 50
Now use the point-slope form to get the equation
y-300 = 50(x-3)
or
y = 50x + 150
now you can easily get the y-intercept (when x=0) as (0,150)
So the plumber charges $150 for a house call, plus $50/hr for labor
for the water tank, it is clear that the y-intercept is 200, since that's where the water level is at time t=0. Now, the volume of water changes by -10 every hour, so that's the slope.
y = 200 - 10t