A construction of the average speed problem. The protractor represented by a semicircle was used to measure the angles with slope values of 17 km/hr, 13 km/hr and 19 km/hr. The horizontal dash line gave the distance fraction 0.255 and the vertical dash line gave the time fraction 0.333. For those who forgot how to construct a graph from math class
Let 20 squares represent 1 hr
Let 20 squares represent 20 km
At the origin, draw a slope of 17 km/hr, rise over run is the slope
At the origin, draw a slope of 13 km/hr
At the end-tip of the 17 km/hr line, draw a slope of 19 km/hr, extend the graph paper when necessary. Then extend the 19 km/hr backward to intersect with the 13 km/hr slope
Then read the intersection coordinates in (x squares, y squares)
Then do ratio x/20, y/20
Then repeat with another set of new numeric information