Information for problems $28$ and $29.$ The planetary speed reducer shown below is used in a cordless screwdriver. An exploded view of a similar Craftsman cordless screwdriver is also provided below.

$(12$ points$)$ Determine the reduction ratio for stage A $.$

$(12$ points$)$ Determine the total reduction ratio for the complete reducer.

$9$A carries planets $7$A and drives sun $10$B

Planet gears $7$

$7$ A carried by $9$A$,$ engages $10$A and $57B$ carried by $9$B$,$ engages $10$B and $5N_7=19$

$9B($hidden$)$ carries planets $7$B and drives output

shaft