Answer: 21 to 18, 21:18, or 21/18
Step-by-step explanation: In this problem, we're asked to use the picture shown to write a ratio comparing the number of shaded parts to the number of unshaded parts.
There are 21 shaded parts and 18 unshaded parts.
This means that the ratio of shaded parts to unshaded parts is 21 to 18. It's important to understand that the ratio 21 to 18 can also be written as 21:18 or 21/18.