Give me a multistep problem that has at least two amounts of elapsed time a problem that require finding a starting time or ending time

i just took the test, the correct answer is ..

1. use the straightedge to draw a line k that passes through a and intersects line j. label the point of intersection as point p.

2. place the point of the compass on point p and draw an arc that intersects line j and k. label the intersections as point q and r.

3. without changing the width of the compass opening, place the point of the compass on point a and draw an arc that intersects line k. label the intersections as point s.

4. place the point of the compass on point q and open it to width qr.

5. with the compass opening set to width qr, place the point of the compass on point s and draw an arc that intersects the arc that was drawn from point a. label the intersection of the arcs as point b.

6. use the straightedge to draw ab ←→.