Steps
So to find the y value of 2/3 the distance from point G to H, firstly we have to find how far away the y values are from each other. G's value is -1 and H's value is 3, therefore the distance in y is 4 units away. Multiply 4 by 2/3:

Now, since from -1 to 3 you are increasing, add -1 and 2 2/3 together:

Answer
The y value of the point that's 2/3 the distance from point G to H is 1 2/3 or 5/3.