SOURCE

<div class="container">
    <div class="item1">item1 item1 item1 item1</div>
    <div class="item2">item2 item2 item2 </div>
    <div class="item3">item3 item3 item3</div>
</div>

.container {
    height: 300px;
    background-color: skyblue;
    display: flex;
    /* width: 500px; */
}
.item1 {
    width: 200px;
    height: 130px;
    flex-basis:0;
    flex:1;
    background-color: orange;
    /* align-self: flex-end; */
}
.item2 {
    width: 50px;
    height: 160px;
    flex-basis:0;
    flex:1;
    background-color: pink
}
.item3 {
    /* width: 100px; */
    height: 100px;
    /* flex-basis:0px; */
    /* flex:1; */
    background-color: palegreen
}