There are different rules when it comes to indices. First of all we will look at the example of multiplying two expressions . For example, y2 x y4 . Here we need to do the addition rule, so add 2 and 4 to get 6. The answer is y6. Another example is y4 / y2. Here we would need to use the subtraction rule, hence 4-2 is 2. So the answer is y2.Another example is (y3)4. Here there is the use of brackets, where an index is inside as well as outside. So the multiplication method is needed, where you would have to do 3 x 4 which is 12. So the answer is y12.