Divisible by 3 but Not by 2

Difficulty: Easy · Topics: Discrete Mathematics, Sets, Counting

The sets

A=\n∈mathbbZ^+ mid n≤ 60,\ n is divisible by 3\

B=\n∈mathbbZ^+ mid n≤ 80,\ n is divisible by 2\

are given. How many elements does the difference set Asetminus B have?