title: how to make $translate.instant interpolation instead of concatenation
body: <p>I am using translate.instant and making a string concatenation like that</p>
  
  <pre><code>var variable = this.$translate.instant('project.discount') + " % " + this.$translate.instant('project.applied_to') + " " +this.office;
  </code></pre>
  
  <p>how can I do that inside one $translate.instant as string interpolation instead of concatenation</p>
  
  <p>Thanks,</p>