just saying the 30:29 is 1:1, [ 1: 1.0344827, by my calculator.. ]

smaller difference between the 39 and the 30 means the low gears
the ratios, are maybe 3 for all the added parts ..
though they ship from the factory with the 30, you can replace the 30t with a 26t and gain a lower ratio.

Granny gear , half the size of the big ring, is good.

10 speed compatible just means the teeth on the chainrings are a little thinner ,
and a bit closer together , to go with the chain needing to be thinner
to go in the narrower space, left by compressing 10 cogs in the same overall width of 8.