3. 11/18 - 4/9 =

Find a common denominator for 18 and 9, which is 18.

Convert the fractions: 11/18 - (4*2)/(9*2) = 11/18 - 8/18.

Subtract the numerators: (11 - 8) / 18 = 3/18. Simplify to 1/6.