Answer: y = 4x
slope = 4
y intercept = 0
====================================================
Explanation:
Two points on this line are (8,32) and (12,48)
Apply the slope formula to get
m = (y2-y1)/(x2-x1)
m = (48-32)/(12-8)
m = 16/4
m = 4
The slope is 4.
Use a point like (x,y) = (8,32) and the slope we found to determine the y intercept b
y = mx+b
32 = 4*8+b
32 = 32+b
32-32 = 32+b-32 ... subtract 32 from both sides
0 = b
b = 0
------------------
We found that m = 4 is the slope and b = 0 is the y intercept
We go from y = mx+b to y = 4x+0, which simplifies to y = 4x
In short: the y coordinate is 4 times that of the x coordinate.
For instance, if x = 16, then
y = 4x = 4*16 = 64
Which leads to the point (16,64)
Note: the slope of 4 means it costs 4 dollars per gallon. We can think of this as the unit rate, or rate of change.
