How many times does the number '7' appear in String a?
1 

Count the total number of letter "F" in the following text:
FINISHED FILES ARE THE RESULT OF YEARS OF SCIENTIFIC STUDY COMBINED WITH THE EXPERIENCE OF YEARS...
This teaser is called "Alzheimer's' eye test".
Consider the calculation as follows :
$\frac{2(X+3)} {Y+9}$ (where X & Y are variables)
Which of the following represents the correct Reverse Polish notation for that calculation :