<style>
.elem {
display: flex;
align-items: center;
}
.cont {
text-align: center;
display: inline-block;
}
.sign {
margin: 0;
height: 1px;
border: none;
background: #000000;
}
</style>
<div class="elem">
<div class="cont">1<hr class="sign">777</div>  + 
<div class="cont">458<hr class="sign">3</div>  − 
<div class="cont">784<hr class="sign">689</div>
</div>