There are three bulbs. Each light bulb can be lit in three colors: red, green and blue.

There are three bulbs. Each light bulb can be lit in three colors: red, green and blue. How many color combinations can you make from these bulbs?

In total, you can make 27 combinations. Since there are 3 light bulbs and 3 colors too, we are cube. It turns out 3 * 3 * 3 = 27
For example:
2 red + 1 green, then the combination changed to green-blue-red, after that one color on the light bulb may change, two remain the same.