Answer:
20 is the rate of change/slope
Your choices of answers are not clear, is the letter x a variable or a multiplication?
If it is possible, take a picture of your question.
The equation would be x+5*-2=6.
The result of that equation would be x=16
Answer:
1)
2) 12 inches tall.
Step-by-step explanation:
1) The equation of the line in Slope-Intercept form is:

Where "m" is the slope and "b" is the y-intercept.
In this case:
(The height of the candle in inches)
(The time in hours)
Then, we can rewrite it:
Based on the information provided in the exercise, the line passes through these points:
and 
Then, we can find the slope of the line with the formula
:

Now we need to substitute the slope and one of the points into
and then solve for "b":

Substituting values, we get that the a linear equation that models the relationship between the heigth of the candle and the time, is:
2) We must substitute
into the linear equation
in order to find the height of the candle after burning 8 hours: