pagina de curso de cenecyt
http://www.alau.ec/minicurso-2/https://www.youtube.com/watch?v=M1UqFlbeCXE
https://www.youtube.com/watch?v=AZGJuOxavVU
http://www.alau.ec/mini973/
http://examen-senescyt.blogspot.com/2013/09/problemas-de-razones-y-proporciones.html
