Find the missing number from the given figure?

Raju ranks 10th from the top and Ravi ranks 21st from the bottom. If there are 3 students between them, how many students are there in the class? 

a_cacbc_baca_ _b 

In a certain code, TRIPPLE is written as SQHOOKD. How is DISPOSE written in that code ?

If COOL is coded as DQRP, then write the code for HOT

If TREK = 8346 and FAMILY =209175 then REALITY will be 

Find the missing Number.

Directions: - In each of the following questions, five words are given. Which of them will come to arrange the following words according to the English dictionary order?
1. Globe 2. Group 3. Glitch 5. Glade