Answer:
1/7
Step-by-step explanation:
Since we do not know the number let us use the alphabet A to represent the unknown number
A × 1/3= 1/21
A/3= 1/21
Cross multiply both sides
A×21= 3×1
21A= 3
Divide both sides by the coefficient of A which is 21
21A/21=3/21
A=1/7
Hence the unknown number is 1/7
Answer: 156.25
Step-by-step explanation:
C= 20-0.75x
c= 20-0.75(9)
c= 20-6.75
c= 13.25
Here c is the amount of change and x is the number of books bought.
The customer's change will be $13.25
