How do you read the word bismillahi majr__ha wa mursaha.....

Question
How will read the word bismillahi majr_ha wa mursaha?

Answer
Assalaam alaikum. 
They riwaayah of Hafs 'an 'Aasim reads the word in surah Hud, aayah 41, with grand imaalah, meaning the alif is read as 50% ya' and 50% alif. 
For further details please see the following:  Lesson on special words
http://www.abouttajweed.com/words-hafs-an-aasim-min-tareeq-ash-shatibiyy/special-words-for-hafs-an-aasim-by-the-way-of-ash-shaatibiy.html