How many moles is 1.50 x 1023 molecules of nh3

1 mole 6.02 x 10²³ molecules
? mole 1.50 x 10²³ molecules

moles = 1.50 x 10²³ * 1 / 6.02 x 10²³

moles = 1.50 x 10²³ / 6.02 x 10²³

= 0.249 moles  

hope this helps!