How to offset a measure's value by another measure

Summary:

We need to offset value of measure A by certain number of days which is specified in another measure

Content (required):

We define 3 measures:

Measure A -- data type: number

Measure B -- data type: number

Measure C - data type: number; this is the offsetting days

The requirement is

Measure B = Measure A offset by Measure C

Any idea?

Version (include the version you are using, if applicable):

21D

Code Snippet (add any code snippets that support your topic, if applicable):