Actually the solution is not so difficult to arrive at. Since
the remainer is the same for all the numbers, the differences
between the numbers should be perfectly divisible by the HCF. In
particular 861-740 = 121, which is 11^2, readily identifying 11 as
the HCF. Applying this to the 3 numbers confirms the
solution..
alternatively you can subtract 3 from each number and write down
all the factors for each, thereby identifying the HCF. For 608 it
would have been very easy because 608 - 3 = 605, telling you
5 is one of the factors. Dividing 605 by 5 = 121, which is 11^2,
thereby identifying 11 as the HCF.
Hope this helps.