What is the index of equation and what does it mean to you in terms of simplifying this expression?

The goal in simplifying numbers is to reduce it that can be best seen in the eye. In here, you are given 5a x 2c x 3d. Note that 5, 2 and 3 are coefficients and a, c and d, are variables. Multiply first the coefficients 5, 2 and 3 and you get 30. Always remember that in multiplying numbers, especially variables, the base of the exponent must be equal. However, you have variables of a, c and, d. You cannot multiply or add them because they are different. So the answer is 30acd.