How to make a math operation on a span tag?

This 2 span tag:
<span class="new-time">25450</span>
<span class="old-time">???</span>

How to make sure to take a value from a span tag with the class new-time, then divide by 2 and substitute in the span tag with the class old-time. That is on the way out. In the browser window, inside ??? instead of characters "???" somehow it must be substituted the value of 12725 (it can be any) (i.e. this value 25450 divided into 2)...
September 18th 19 at 23:45
1 answer
September 18th 19 at 23:47
$('.old-time').text(($('.new-time').text() / 2.0));

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