Answer:
Credit remaining after 21 minutes = $30.4
Step-by-step explanation:
Credit remaining on a phone card is a linear function of the total calling time.
When graphed, let the linear function representing the line is,
y = mx + b
Where 'm' = slope of the line
b = y-intercept
From the graph,
Slope of the line = -0.12
y = -0.12x + b
If this line passes through a point (33, 28.96),
28.96 = -0.12(33) + b
b = 28.96 + 3.96
b = 32.92
Therefore, the linear function is,
f(x) = -0.12x + 32.92
where x = calling time
Credit left in the card after 21 minutes,
f(21) = -0.12(21) + 32.92
= -2.52 + 32.92
= $30.4
B. (k+10f)(k-5f) you can tell in 2 ways. 1. if the second sign is neg then the signs in the factors are going to be one neg and one positive so that knocks out C and D. Then you look at the second term and since the 5 is positive then the 10 has to be positive so you end up with a positive 5kf.
The second way is to FOIL them out. When you check B you get

combine your like terms and you have your original expression of

Hope that helps
Answer:
0
Step-by-step explanation:
Answer:
- 1) y = 13.5x + 1
- 2) y = 12x + 4
- 3) Sam won the race
Step-by-step explanation:
<h3>Part 1</h3>
Sam's car is 1 ft in front of the start line and its speed is 13.5 ft/s.
<u>The distance after x seconds is:</u>
<h3>Part 2</h3>
Alice's car the speed 12 ft/s and after 3 seconds is 40 ft in front of the start line.
<u>The distance after x seconds is:</u>
- y = 12(x - 3) + 40 = 12x - 36 + 40 = 12x + 4
<h3>Part 3</h3>
<u>After 15 seconds the distance from the start line is:</u>
- Sam ⇒ y = 13.5*15 + 1 = 203.5 ft
- Alice ⇒ y = 12*15 + 4 = 184 ft
As we see Sam is further from the start line than Alice