First, we must find the equation of the given line. The slope is "rise over run," or the change in y over the change in x from one point to another. The two points shown are (0,-1) and (3,1). In these points, y increases by 2. This means the change in y is 2. In these points, x increase by 3. This means the change in x is 3. Thus, the change in y over change in x is 2/3. This means that the slop of the given line is 2/3.
In the form y=mx+b, where m is the slope, b is the y intercept. This is because the y intercept occurs when x is 0. If x is zero, mx is zero, so y=b. In other words, when x equals 0, y=b. This creates the point (0,b), which is the y-intercept. Since the y-intercept of the given line is -3, the equation for this line is: y=2/3x-3.
A line parallel to this will need to have the same slope. This allows us to eliminate choices C and D, which do not have the same slope.
In order for the line to have an x-intercept of (-3,0), y must equal 0 when x is -3, since ordered pairs are (x,y). We can solve the equation using the information we know: 0=((2/3)(-3))+b This is because we know the slope is 2/3, and that when x is -3, y is 0.
Then, we can solve from there: 0=(-2)+b (just multiply 2/3 and -3) 2=b (add 2 to both sides)
Since she estimated 69%, you could do either of these options. You could... A. Divide 242 (or .5) to show how much half off would be, then compare her estimate with half of 242 (121). OR... B. Simply divide 242 by 69% (.69) and compaor her estimate to the exact amount (166.98).
