Edit in JSFiddle

<h2>
Flex-Direction Row
</h2>
<div class="flex-container">
<div class="item basis-5">500px</div>
<div class="item">1</div>
<div class="item">1</div>
<div class="item">1</div>
</div>

<h2>
Flex-Direction Column
</h2>
<div class="flex-container column">
<div class="item basis-2">200px</div>
<div class="item">1</div>
<div class="item">1</div>
<div class="item">1</div>
</div>

*{
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}
*::before, *::after{
  box-sizing: border-box;
}
.flex-container{
  display: flex;
  width: 700px;
  max-width: 100%;
  padding: 15px;
  border: 2px solid;
  margin-bottom: 10px;
  
}
.flex-container.column{
  flex-direction: column;
}
.item{
flex-shrink: 1;
flex-grow: 1;
  text-align: center;
  background-color: #2da192;
  color: #fff;
  margin: 5px;
  font-size: 30px;
  line-height: 80px;
  font-weight: 600;
}
.basis-5{
  flex-basis: 500px;
  background-color: #f11a56;
}
.basis-2{
  flex-basis: 200px;
   background-color: #f11a56;
}