The equation c=1500+250x represents the cost, c, of making x televisions for Company A. The equation

The linear equations are given in the slope-intercept form
y = mx + b

In this case y = c, obviously to indicate the meaning of this value: cost.
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m is the slope or gradient, the "steepness" of the graph.
If the slope m = 0, then the mx-term equals 0 and the graph is a parallel to the x-axis.
If m < 0 then mx is negative and the graph is descending in the direction of increasing x.
If m > 0 then mx is positive and the graph is ascending in the direction of increasing x.

The amount |m| signifies the steepness -- the greater, the steeper --, but whether the graph is going up (+) or down (-), depends on the sign.
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b is the y-intercept (well, the c-intercept in this case), the point where the graph crosses the y-axis (0 , b).

If b = 0 , the graph crosses the y-axis at the Origin O(0 , 0).

The greater the value of b, the farther away from the origin will the graph pass the y-axis (c-axis in this example), above the origin if b > 0 and below if b < 0.
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You've to compare two graphs of linear equations A, B.
A) c = 250x + 1500
B) c = 150x + 2500

Now you can just read the answer from the values of the equations:

C) The graph representing Company B will be flatter (as 150 < 250) and start higher on the y-axis (as 2500 > 1500).

It's as simple as that ;)