Income from hp-vacancy loss -confusion ?

Hello everyone,

i have confusion adjustment of vacancy allowance for computing income from house property

1. In one of the book (ainapure-tybaf, mumbai university)income has been calculated as follows :

I.Reasonable letting value              150

II.acutalrent(vac.loss-10)                130

III.gross annual value =                    150

Reason : (since RLV is higher than actual rent and even if there is no vacancy loss ie. 130+10=140, still RLV would have been greater than the acutal rent recd/receivable. If acutal rent would have been lower than the RLV on account of vacancy then actual rent although less than the RLV still actual rent would have been taken as GAV)

2. However in VK singhania treatment is different 

I.Resonable letting value                      150

II.actual rent received/receivable       140

III.Higher of I OR II                                     150

IV LESS: vacancy loss                             10

v III-IV = GROSS ANNUAL VALUE            140

(Every problem has been solved in the above format and there was no mention of taking actual rent as GAV if the same is lower than the RLV on account of vacancy which was mentioned in the 1st case)

which one is correct. 

waiting for views of the experts.