The given graph shows the cost for renting a post hole digger from a local hardware store. We have to determine the rate of change or cost per day.
Let us consider any two points.
Let us consider (1,30) and (2,60)
We have to determine the rate of change which is basically termed as "slope".
Rate of change is expressed as a ratio between a change in one variable relative to a corresponding change in another variable.
Therefore, rate of change or cost per day =
Change in y 
Change in x
= 
= 30
Therefore, the rate of change or cost per day is $30 per day.
Answer:
Purple line: 4
Red dashed line: 2
Blue line: 1/2
Step-by-step explanation:
The purple line is the steepest line, therefore it has the biggest constant of proportionality or slope. Since 4 is the biggest number among the others, we attribute it to the purple line (the one with the point C on it).
Think of it this way:
here 
so 
The greater a is, the greater y is. So for any value of x, y will be become bigger and bigger if we increase the value of a.
Take for example this one:
Take 
therefore 
Now take 
and take 
therefore 
When we increased this constant of proportionality, as you can see from 2 to 4, the value of y increase from 4 to 8.
Hope this is helpful. Think of it really carefully, and I'm sure you'll grasp the concept.
982 or 980 depending on where you are rounding to...
Currently there are 28 children playing. Until a moment ago, 4 of those 28 werent there. To find out how many there were a moment ago, we have to exclude those 4 kids that just came — or subtract the number of kids that just came from the number of kids currently playing.
28-4=24
We can check: 24+4=28
