Given expression = 3 gross 2 dozen 4 ones - 7 dozen 6 ones.
Now, 3 gross = 3 x 12 dozen = 36 dozen.
So, 3 gross 2 dozen = 36 + 2 = 38 dozen.
Now, 38 dozen 4 ones = 38 x 12 + 4 = 456 + 4 = 460 ones.
Finally, 460 ones - 7 dozen 6 ones
= 460 - (7 x 12 + 6)
= 460 - (84 + 6)
= 460 - 90
Therefore, the result of the given expression is 370.