Question for the lawyers of the OT.

Let's just say a company was purchased for 3.5 million. The previous owner would hold on to 10%. The other 90% would be owned as such:
One owner , who already was gifted 10% years ago , now owns 51% without putting up any cash. (I'm not sure how the transaction went down but I do know he now owns 51% of the company)
Owner 2: Owns 40% of said company and put up $300,000.00 to obtain that 40%.
When original owner (owns 10%) dies the 2 other owners or the business get first option on the 10%
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My question is this: How much say/power does the 40% owner have in said company? The 51% owner is running the (once very lucrative business ) into the ground. My fiancé is the 40% owner and she claims she cannot do or say anything to change things because her partner owns a majority of the business. I may be dumb , I'll take that if true , but I think that as an owner , especially at 40% , she should be able to dictate , to an extent , what goes on business wise.
Is it cut and dry that the majority owner gets to make all decisions , good or bad , while the 40% owner just has to sit back and wait to find majority owner fricking up before she can do anything?
I understand that the majority owner has more stake in the company (albeit without putting up any cash) and it would seem , more decision making power. But how does that shake out? Surely , the other big owner (40%) has some kind of say in day to day operations, right?
I can explain more if needed. Much more when it comes to the problems that the company is having and the dumb decisions being made by Mr. 51%. I'm just a wanting to know how much weight she has and , if none , what her right course of action may be without bringing down the company because I believe that if it comes to that , she'd be brought down as well being a stupid (I'll just keep my mouth shut) partner.
I know tl/dr. If anyone does read , it would be appreciated. No need for the dumb fricks and they're dumb responses! Trying to get some real guidance here. Thanks