No one seems to have submitted a correct solution for problem #75 about
drawing a triangle cut into 13 congruent triangles.  So here's a hint.

It's easy to cut any triangle into 4 congruent triangles: draw the line
segments connecting the midpoints of the three sides.

13 = 4 + 9

End of hint.

(Jim Conklin wins the prize for problem #74, the marathon.)

CCHanna