1) place the compass needle on the external point r.2) make the compass width greater than the distance from r to the given line. 3) draw an arc cutting the given line at two points. 4) mark and label the points of intersection p and q. 5) without changing the compass width, move the compass needle to q and draw another arc below the line crossing the previous arc. 6) move the compass needle to p and make an arc below the line. 7) mark and label the point of intersection s. 8) draw a line from the external point r to the point where the arcs intersect, s. 9) line rs is perpendicular to line pq and passes through the external point r.
To get the answer we can use proportion. 30----------100% 12-----------x Cross multiply now 30x=12*100% 30x=1200% /:30 (divide both sides by 30) x=40% - it's the percentage of cars which finished the race. 100%-40%=60% - it's the answer
