There were 75 runners to start a race. in the first half of the race 1/5 of them dropped out. in the second half of the race 3/5 of the remaining runners dropped out. how many runners finish the race

The pyraminx is a rubik's cube-type toy in the shape of a tetrahedron. the pyraminx shown below has edges 15\,\text{cm}15cm long and vertical height h=12.2\,\text{cm}h=12.2cm. the triangle drawn with dashed lines is a right triangle. what is the distance rr? round your answer to the nearest tenth.