Dierdre’s work to solve a math problem is shown below.

Problem: How many 1 and one-half-foot pieces can be cut from a 12-foot length of ribbon?
Step 1:
1 and one-half divided by 12 = n
Step 2:
Three-halves divided by 12 = n
Step 3:
Three-halves times StartFraction 1 Over 12 EndFraction = n
Step 4:
StartFraction 3 Over 24 EndFraction = n
Answer:
One-eighth = n

What was Dierdre’s first error?
She switched the divisor and the dividend in step 1 when creating an equation to model the problem.
She used an improper fraction in step 2 that is not equivalent to 1 and one-half.
She replaced the divisor by its reciprocal in step 3 instead of replacing the dividend by its reciprocal.
She reduced the fraction in step 4 incorrectly.