The specified letters are R, C, H, A and I. The only meaningful word  that can be made is CHAIR. The third letter of this word is A.

6th to the left of 17th letter to the right of 7th letter from the left = 6th to the left of (17+7 =) 24th letter from the left = (24-6 =) 18th letter from the left.

Thus, we have to count from the left and we have to find out 18th letter from the left that falls into the second section of English alphabet.

Here, both the first half and the second half of the English alphabet have been reversed and we have to count from the left end, then the required letter can be found out using the formula given below. Suppose , the first and the second reversed sections of the English alphabet are α and  βrespectively.Then,

  The required letter = 2α+β+1-(required position of letter from left side)

Therefore, The required letter = 26 + 13 + 1 - 18 = 22 = V

Second vowel from the right of reversed English alphabet is E and 7th letter to the left of E in the new series is L.

2nd letter to the left of 17th letter from the right means (2 + 17 = ) 19th letter from the right = (26 - 19 + 1 =) 8th letter from the left end , i.e H.  Thus, 8th letter falls into the second section of the reversed sequence. Now, the sequence FGHIJ is reversed and becomes JIHGF. Clearly, position of H remains unchanged. Hence the required letter is H.

4th to the right of 20th letter from the right means (20 - 4 =) 16th from the right.

16th letter from the right = (26 - 16 + 1 =) 11th from the left, i.e K

If the first half of the English alphabet is reversed and the remaining part has been left undisturbed, then it becomes very easy to find out the required letters, if required letters come in the first half. According to the question, 10th to the left of 16th letter from the left = (16 - 10 =) 6th letter from the left in new series.

=>  6th letter from the left in new series = (13 + 1 - 6=) 8th letter from the left in the original series, i.e H.

The given word is VITREOUS. Of which , TRSV are the consonants and IEOU are the vowels. Now, after making the changes as given in the question  we get following arrangment: RSTVEIOU.

Again from precalculation, we know that second to the right of fourth  from the left means (2+4=) 6th from the left. i.e I

Given word is O B S E R V A N T. After making the change as given in the question, we get the following arrangement:

T N A V R E S B O.