As posted before by Peter, you can find a Yeast Conversion Table here. http://www.theartisan.net/convert_yeast_two.htm
where 1.7gm of cake yeast (CY) = 0.7gm ADY = 0.5gm IDY. From these numbers I found conversion factors for....
CY to ADY = 0.4117
CY to IDY = 0.294
ADY to IDY = 0.714
IDY to ADY = 1.4
ADY to CY = 2.43
IDY to CY = 3.4
So lets pretend a recipe calls for 1700gm of flour and 0.3% of CY. And you would like to use ADY or IDY.
To convert CY to ADY or IDY, just use the conversion factors listed above.
So to convert 0.3% CY to ADY, you would do it like this....
0.3% CY of 1700gm Flour => 0.003 x 1700 = 5.1gm of CY
5.1gm CY x 0.4117 = 2.09gm ADY
You can also take 0.3% CY x 0.4117 = 0.123% ADY. To check our math,
0.123% ADY of 1700gm flour => 0.00123 x 1700 = 2.09gm ADY
Of course you can always use the table if you don't want to do math, but I find doing the math easier. Of course, the easiest way to do conversions is if Peter or someone can come up with a Yeast Calculating tool whereby users can just plug in numbers like the dough calculator.
Let me know if my math is off.