The answer is b because it has the 3 with 6 corresponding.<span />
The answer is 3 and 5/6 because 6 goes into 23 3 times with 5 left over. then you put the five over the denominator 6. make sense dear?
Take an example: The salary per hour:
Assume x (variable) is the number of hours worked and assume THAT THE RATE PER HOUR IS $10, then:
If you work x hours at the hourly rate of$10, you will generate an income,
say, y that is equal the number of hours worked by the rate per hour, that is:
y = 10.x. The more hour(x) you work, the more income(y) you get.
Hence we created a relationship between y and x , or in English, between the earning and the number of hours worked.
Moreover y depends on x, if there is no x, there is no y and if x increases, y increases. However x is an INDEPENDENT variable because you can
give to x any number & y will follow
Solution:
As we given that
then using this conversion factor we can write 
and further it can be written as

Hence the required conversion factor is 2.54 cm/1 inch as we can see from the above calculation.
10 is the answer................