Answer:
(0, 7000); (10, 18000)
Step-by-step explanation:
Lets first start by breaking the problem down
Breaking the problem down
We add 1100 gallons for every hour
The pool already contains 7000 gallons
Our goal is 18000 gallons.
Make an equation
y = mx + b
In this case we're lucky as all of these are given.
Our slope of m is how many of gallons we gain for every x value (hours)
So plugging it in we can rewrite it so far as
y = 1100x + b
Now our b value is our y-intercept which is what we start with at x = 0 which is also where the value touches our y-axis.
In this case at 0 hours passed we have 7000 gallons thus 7000 is our b.
We can plug it in and rewrite as follows
y = 1100x + 7000
Now what we want to solve for is our y so we plug 18,000 in for y and solve by getting x alone
y = 1100x + 7000
18000 = 1100x + 7000
-7000 -7000
11000 = 1100x
Divide both sides by 1100 and you have your hours until its full
10 = x
So at 10 hours the 18000 gallon pool will be full,
As such we can determine our second point as (10, 18000)
Now because we know our y-intercept we can use that to find the other point.
The line intercepts the y axis (0, y) at 7000, and as such our point is
(0, 7000)
Putting them together we have point A and point B solved
A(0, 7000) B(10, 18000)
Note the points are (x value, y value)
Hope this helps, if you have any more trouble leave a comment and I'll help you further