In the following question, the sentence given with blank to be filled in with an appropriate word. Select the correct alternative out of the four and indicate it by selecting the appropriate option.
It is ______ for all the students to follow the rules.
A word is represented by only one set of numbers as given in any one of the alternatives. The sets of numbers given in the alternatives are represented by two classes of alphabets as shown in the given two matrices. The columns and rows of matrix-I are numbered from o to 4 and the matrix-II are numbered from 5 to 9. A letter from these matrices can be represented first by its row and next by its column, for example, F can be represented by 13, 21 etc and Y can be represented by 97,98 etc. Similarly, you have to identify the set of the word 'TONE'
A man has some hens and some cows. If the total number of heads of hens and cows together is 50 and the nunber of feet of hens and cows together is 142, then the number of cows is