Answer:
A and C the first and third cause when u are finding the y-intercept you have to put x as zero
Intersection of the first two lines:
Multiply the first equation by 4 and the second by 5:
Subtract the two equations:
Plug this value for y in one of the equation, for example the first:
So, the first point of intersection is 
We can find the intersection of the other two lines in the same way: we start with
Use the fact that x and y are the same to rewrite the second equation as
And since x and y are the same, the second point is 
So, we're looking for a line passing through and . We may use the formula to find the equation of a line knowing two of its points, but in this case it is very clear that both points have the same coordinates, so the line must be 
In the attached figure, line 
is light green, line 
is dark green, and their intersection is point A.
Simiarly, line 
is red, line 
is orange, and their intersection is B.
As you can see, the line connecting A and B is the red line itself.
Assume that the rule connecting height of the candle to time is a linear one. If you do, then we have to find the equation of this line, and then use this equation to predict the height of the candle after 11 hours.
Two points on this line are (6,17.4) and (23, 7.2). The slope is thus
7.2-17.4 -6
m = --------------- = ----------- or -3/5.
23-6 10
Find the equation of the line. I'm going to use the slope-intercept formula:
y = mx + b => 7.2 = (-3/5)(23) + b. Solving for b, b = 21.
Now we know that y = (-3/5)x + 21
Let x=11 to predict the height of the candle at that time.
y = (-3/5)(11) + 21 = 14.4 inches (answer)
T = na
because, total equals to ounces of the material times the amount payed.
