In the future, please post the full problem with all included instructions. After doing a quick internet search, I found your problem listed somewhere else. It mentions two parts (a) and (b)
Part (a) asked for the equation of the line in y = mx+b form
That would be y = -2x+9
This is because each time y goes down by 2, x goes up by 1. We have slope = rise/run = -2/1 = -2. This indicates that the height of the candle decreases by 2 inches per hour. The slope represents the rate of change.
The initial height of the candle is the y intercept b value. So we have m = -2 and b = 9 lead us from y = mx+b to y = -2x+9
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Part (b) then asks you to graph the equation. Because this is a linear equation, it produces a straight line. We only need 2 points at minimum to graph any line. Let's plot (0,9) and (1,7) on the same xy grid. These two points are the first two rows of the table. Plot those two points and draw a straight line through them. The graph is below
Answer:
1) The discount is $4.05
The sale price is $18.45
2) The discount is $10
The sale price is $30
3) The discount is $2.6
The sale price is $23.4
Step-by-step explanation:
1) What is the discount and sale price for a haircut that originally cost $22.50 with an 18% discount.
Actual Price= $22.50
Discount = 18%
Finding discount:

So, the discount is $4.05
Finding Sale Price
The sale price can be found by: 
Putting values and finding sale price:

The sale price is $18.45
2) What is the discount and sale price for a sweatshirt that originally priced $40.00 with an 25% discount.
Actual Price= $40.00
Discount = 25%
Finding discount:

So, the discount is $10
Finding Sale Price
The sale price can be found by: 
Putting values and finding sale price:

The sale price is $30
2) What is the discount and sale price for a large pizza that originally cost $26.00 with an 10% discount.
Actual Price= $26.00
Discount = 10%
Finding discount:

So, the discount is $2.6
Finding Sale Price
The sale price can be found by: 
Putting values and finding sale price:

The sale price is $23.4
Answer: 500
Step-by-step explanation:
2 sets of 25 pushups in 1 month
He does it ten times per month
2*25*10
500