simple if or condition code

hi ,

i have an attribute blocks and this att block has two tag values , is there a simple code for tochange 1st tag values automaticly according to  2nd values ?

for example :

1st tag (50x50) - 2nd tag ( 100 )    ==> 50x50-100

if i enter 201 valuse to 2nd tag then 1 st tag has to change as 100x100

if i enter 501 valuse to 2nd tag then 1 st tag has to change as 150x510

i attached a jpg file for explain much better

thank you

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