Generated by SassMeister.com.

SassMeister-input-HTML.html

<div class="container">
  <div class="sixpack--1">
    <div class="tile tile--1">tile 1</div>
    <div class="tile tile--2">tile 2</div>
    <div class="tile tile--3">tile 3</div>
  </div>  
</div>

SassMeister-input.scss

// ----
// Sass (v3.4.14)
// Compass (v1.0.3)
// ----

* {
  box-sizing: border-box;
}

.container {
  background-color: blue;
  width: 900px;
  height: 900px;
}

@mixin tile($width, $height) {
  width: percentage($width / 2);
  padding-top: percentage($height / 3);
}

.sixpack--1 {
  .tile--1 {
    @include tile(2, 3)
  }
  
  .tile--2 {
    @include tile(2, 2)
  }
  
  .tile--3 {
    @include tile(2, 1)
  }
}

.tile {
  background-color: red;
}

SassMeister-output.css

* {
  box-sizing: border-box;
}

.container {
  background-color: blue;
  width: 900px;
  height: 900px;
}

.sixpack--1 .tile--1 {
  width: 100%;
  padding-top: 100%;
}
.sixpack--1 .tile--2 {
  width: 100%;
  padding-top: 66.66667%;
}
.sixpack--1 .tile--3 {
  width: 100%;
  padding-top: 33.33333%;
}

.tile {
  background-color: red;
}

SassMeister-rendered.html

<div class="container">
  <div class="sixpack--1">
    <div class="tile tile--1">tile 1</div>
    <div class="tile tile--2">tile 2</div>
    <div class="tile tile--3">tile 3</div>
  </div>  
</div>