First you have to figure out what the equation of the line is. Let's use the slope formula to find the slope, and then one of the points to find the y-intercept. We'll put the line's equation in y=mx+b form.
[tex]slope = \frac{ y_{2} - y_{1} }{ x_{2} - x_{1} } \\ slope = m \\ m = \frac{5 - 1}{-7 - 1} \\ m = \frac{4}{-8} \\ m = - \frac{1}{2} [/tex]
Now, we'll use that slope in y=mx+b form with one of the coordinates in order to find what b (which is also the y-intercept) equals
[tex]y = - \frac{1}{2}x + b \\ 1 = 1(- \frac{1}{2}) + b \\ 1 = - \frac{1}{2} + b \\ 1 \frac{1}{2} = b [/tex]
therefore your y-intercept is equal to 1.5. In order to find the x-intercept we'll take our new equation [tex]y = - \frac{1}{2} + 1 \frac{1}{2} [/tex] and make y = 0, because the line intersects with the x-axis when y is equal to zero.
[tex]y = - \frac{1}{2}x + 1 \frac{1}{2} \\ 0 = - \frac{1}{2}x + 1 \frac{1}{2} \\ -1 \frac{1}{2} = - \frac{1}{2}x \\ x = 3[/tex]
therefore, your x-intercept is 3 and your y-intercept is 1.5
