the rope is 1 and 1/3 long,1 is the same as saying 3/3,
this means that the rope is 3/3 + 1/3 long,so it is 4/3 foot long,
you now want to get half of this number so that each person has an equal length of rope,so multiply the length of rope by a half,
4/3 x 1/2 = 4/6 , which if simplified = 2/3, this means that each friend gets 2/3 foot of rope.
You can draw this in a diagram by drawing the 1 foot of rope, and then dividing it up into 3 sections. Then add the 1/3 foot of rope into the drawing. It should then be easy to see that altogether there are 4 separate sections of rope and that if each friend has two sections then they will be sharing equal amounts, so consequently each friend has two of the thirds of rope, 2/3
