Final answer:
The original piece of yarn was 27 inches long. After cutting it into three equal parts and trimming one part by 5 inches, the remaining length of that part was 4 inches. Tripling this length (9 inches) gives the original length.
Step-by-step explanation:
The student's question involves finding the original length of a piece of yarn after certain operations have been performed on it. The yarn was first cut into three equal pieces, and then one of the pieces was shortened by cutting off 5 inches, resulting in a piece that was 4 inches long afterwards.
To solve this, we need to work backwards and find the length of the yarn piece before it was cut. Since 4 inches remained after cutting off 5 inches, we understand that the piece was originally 4 inches + 5 inches = 9 inches long. This 9-inch length represents one-third of the original yarn's length, as it was divided into three equal pieces.
Therefore, the original length of the yarn would be three times this 9-inch piece, which is 9 inches × 3 = 27 inches. Thus, the original piece of yarn was 27 inches long.