The different between twice a number and a number that is 5 more than it is 3. 1) 2n-n+5=3. 2) n-(2n+5)=3. 3) n+5-2n=3. 4) 2n-(n+5)=3

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.