Confused about 3 div row set up

I’m trying to create a row of 3 divs (so they can be responsive and break into a column of 3 divs for mobile) with one floating left, one floating right and another in the centre but I cannot for the life of me get it to work and I’m not seeing how to make it work with div up!

This is what I’m trying to achieve:

[ [div-1] [div-2] [div-3] ]

This is what I’m getting:

[ [div-1][div-2]
[div-3] ]

(doesn’t show correctly when posting but div-3 is below 1 and 2 floating to the right and div-2 seems to float left rather than being centered)

Am using Headway Themes and this is the CSS although it changes all the time as I have tried everything!!

.container-div {
clear:both;
width: 100%;
}

.divup-wrap-2 {
width: 25%;
float:left;
margin:10px;
}

.divup-wrap-3 {
width: 25%;
display: inline-block;
margin: auto;
}

.divup-wrap-4 {
width: 25%;
float:right;
margin:10px;
}

Please help!

https://www.ads-software.com/plugins/divup-content/