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.