4 2/3 - 1 2/3 is 3.
When you subtract normally, 2/3 - 2/3 cancels each other out, resulting in an answer of 0.
(2/3 -2/3)
After subtracting your numerator and denominator, all is left to do is subtract 4-1 to get 3 as your whole number, or in this case, your answer.
4-1=3