Subtraction in CDS view

Hi Experts,

I am posting here first time. 

I have created a CDS view in ECLIPSE. Sharing this view as an image.

Here I have dynamic fields like GOODS_RECPT & GOODS_ISSUE. I want to make a new field which will be subtraction result among them.

Like example: new f1 = GOODS_RECPT - GOODS_ISSUE.

Currently this code working properly and getting result as expected.

Is it possible to make this in CDS view? Because I cant do this. If not possible, then could any one please provide any suggestion to achieve this.

Thanks,

Arindam.