3x - y = 7 6x - y = 10 when solving this system of equations by elimination, which could be the resulting equation when a variable has been eliminated? a) 9x - 2y = 17 b) -3y = 24 c) -3x = -3 d) 9x = 17

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.