MBa(OH)2 = ABa + 2AO + 2AH = 137 + 2*16 + 2*1 = 171 (this is the molecular mass for barium hydroxide)

in 171 grams of Ba(OH)2... there are... 137 grams of Ba
in x grams of Ba(OH)2... there are... 3.94 grams of Ba

From now on I think you can find the quantity of Ba(OH)2

Good luck! :)

This is similar to the other question:

1. calculate the molecular mass for Ba(OH)2 = 171
2. in 171 grams of Ba(OH)2... there are... 137 grams of Ba
in 1.82 grams of Ba(OH)2... there are... y grams of Ba