Answer :
ANSWER
Each yard cost $6.00
EXPLANATION
If 3 1/2 yards cost $21.00, we have to divide the total cost by the number of yards bought to find the cost of 1 yard.
To do the division first we have to change the mixed number into an improper fraction:
[tex]3\frac{1}{2}=3+\frac{1}{2}=\frac{3\cdot2}{2}+\frac{1}{2}=\frac{6}{2}+\frac{1}{2}=\frac{7}{2}[/tex]Now do the division with the KCF rule:
Keep the first fraction
Change the division sign into multiplication sing
Flip the second fraction
Here the first fraction is a whole number, it means that the denominator is 1:
[tex]\frac{21}{1}\colon\frac{7}{2}=\frac{21}{1}\times\frac{2}{7}=\frac{21\times2}{1\times7}=\frac{42}{7}[/tex]Now we can simplify this fraction, because 42 is a multiple of 7. So, dividing both numerator and denominator by 7 we have:
[tex]\frac{42}{7}=\frac{6}{1}=6[/tex]