12/3 or the same thing as ur question but just add a division sign, eg. difference of two and one that would be 2-1
Answer:
The 2-yard pièce of cotton cloth for $13.26
Step-by-step explanation:
2 yards is 6 feet then it would be $2.21 per foot.
The 17 foot piece would cost $3.29 per foot.
Answer:
Modification has not reduced the number of accidents.
Step-by-step explanation:

A B C D E F G H
Before modification 5 7 6 4 8 9 8 10
After modification 3 7 7 0 4 6 8 2
Difference -2 0 1 -4 -4 -3 0 -8
Mean of differences 
Standard deviation of differences = 
Formula of paired t test :

Df = n-1 = 8-1 =7

t critical> t calculated
So, We failed to reject null hypothesis
Hence modification has not reduced the number of accidents.
The answer your looking for here is 1