In this case the temperature depends on the hour. So temperature is your X and hour is your Y variable. When h=0, x=0. So the 21*C is you x=0 or y-int point.
If we are trying to match the equation for a line of y=mx+b, 21*C=b.
Our rate of change is -4*C/h, which is our m variable.
So y=(-4)x+(21)
OR in this case, t=-4h+21.
Answer D.
Greater than 100 but less than 150
Start with y = mx + b. Subst. -34 for m and 5 for b: y = -34x + 5
The answer would be 93% because first we need to do the reverse of how to find the mean... 80 * 4 = 320 and so we just have to subtract the grades from 320... 320 - 79 - 66 - 82 = 93... Thus Jordan's grade was 93
The correct option is: B. 
<u><em>Explanation</em></u>
<u>The general form of growth equation</u> is:
, where A = final amount, P = initial amount, r = growth rate in decimal form and t = time duration
Here, the speed of the rocket at the beginning was 5,000 kilometers per hour and at the end will be 25,000 kilometers per hour. The speed increases at a rate of 4.3% per minute.
That means, 
Now <u>plugging these values into the above equation</u>, we will get......

So, the equation that could be used to determine the time for the speed of the rocket to reach 25,000 kilometers per hour will be: 