CSS Flexbox: How to align buttons on center

HTML-CSS
5

I tried to do what you told me as goes ` 

            <button type="button" class="btn btn-primary btn-lg">Large button</button>
            <button type="button" class="btn btn-secondary btn-lg">Large button</button>
    
   
</div>`

But that still didn’t do what I wanted
What I’m trying to do with my buttons is something like this

35%20PM