Adding 2 x cells values by entering text in another cell

[swordsong]

Good Day to you all.

Please be advised that I have a situation whereby I need to be able to add 5% to a cell value, and control the total by adding a 'y' in a box to trigger the calculation.
For example -
[TABLE="width: 192"]
<colgroup><col width="64" style="width: 48pt;" span="4"> <tbody>[TR]
[TD="class: xl65, width: 64, bgcolor: transparent"]Volume[/TD]
[TD="class: xl66, width: 64, bgcolor: transparent"]+5%[/TD]
[TD="class: xl65, width: 64, bgcolor: transparent"]Plus 5% ?[/TD]
[TD="class: xl67, width: 64, bgcolor: transparent"]Total[/TD]
[/TR]
[TR]
[TD="class: xl65, bgcolor: transparent"] [/TD]
[TD="class: xl65, bgcolor: transparent"] [/TD]
[TD="class: xl65, bgcolor: transparent"] [/TD]
[TD="class: xl67, bgcolor: transparent"] [/TD]
[/TR]
[TR]
[TD="class: xl65, bgcolor: transparent"]1000[/TD]
[TD="class: xl65, bgcolor: transparent"]50[/TD]
[TD="class: xl65"]y[/TD]
[TD="class: xl67, bgcolor: transparent"]1050[/TD]
[/TR]
</tbody>[/TABLE]

Any help would be very much appreciated,

Best Regards,

 

[Special-K99]

Assuming Volume is in A1

in D3
=A3+IF(C3="y",B3,0)