ANSWER
Option d is the correct equation:
Step-by-step explanation
Let's say that Santi painted "n" stripes. If each stripe is 1/18 yard thick, then the total thickness of all n stripes is,
If he painted the complete height of the post, then this must be equal to 5/6 yards,
If we want to find n, the number of stripes, we have to divide both sides by 1/18,
To solve this, change the division sign into a multiplication sign and flip the second fraction,
18 is divisible by 6, so we can simplify this before multiplying,
Hence, the correct equation is,