Final Fantasy Hacktics

I am confused about Magic Attack Up and Strengthening abilities.

For example: if a black mage has fire rod, black robe, 108 gems equipped and uses fire. How strong becomes the fire magic attack? I am confused because if a wizard is equipped with fire rod, black robe and 108 gems, is the fire attack strengthen by 3x?? (Hope this makes sense)

And how much stronger does a magic attack become with magic attack up? THANK YOU!!!

ele boosting boosts the element by 25%, and does not stack with itself (fire rod + black robe + 108 gems is overkill -- thus black robe + magic gauntlet is a better than wizard robe + 108 gems, if given the option)

MAU boosts magic output by 33.  

They do stack, multiplicatively, but the game does truncate between steps.  A 9 MA unit with ele boosting has an effective MA of 11.

Thank you philsov!