JavaScript variable calculation not working

I’m new to javascript. I want to perform an arithmetic calculation between two javascript values as follows.
In here “issues” and “re” contains numeric values. Then I want to deduct “re” from “issues” and assign the outed value to “#bal”.

Tried

$('#bal').text(jData.data.issues - jData.data.re);

Output

outs ‘0’

What may be going wrong with me ? Ca anyone help me ?