They are both correct about the answer. The answer is 8/3 or 2 2/3
Laura:
As she says it is 2/3 of 4, of is a way of saying you're multiplying.
To see that they are correct, let's us it.
Let's see what is one third of 4.
4÷3= 1 1/3
Now multiply it by 2.
1 1/3 × 2 = 2 2/3
Sean:
It is 4 groups of 2/3. Let's take another example, 2×3. It is 2 three times (2+2+2) and 3 two times (3+3). So the same can be used for 2/3 × 4.
2/3+2/3+2/3+2/3= 4/3+4/3=8/3= 2 2/3.