To find the slope of a line given two points, you should use the formula, Slope=y2-y1/x2-x1.
In this exercise is given the coordinates of two points and it is asked to find the slope of the line which intercepts both points, which are (1,7) and (10,1). To find the slope, you should substitute the given coordinates into the previous mention formula.
If she runs half the distance to school, and runs the same back, this means that she suns 7/8 miles in a day. In 5 days, 5 x 7/8 = 35/8 miles (or 4.375 miles in 5 days).