-b
We are looking for 5 consectuvie numbers, none of those numbers shall be a multiple of 10.
The possible sequences are 1 to 5, 2 to 6, 3 to 7, 4 to 8 and 5 to 9 and all the ones with added multiples of 10 (multiplicator*10)!
There sums will be 15, 20, 25, 30 or 35 or plus 50*multiplicator.
Since no odd sum could be divided evenly by a even ending digit, the sequences with 1 to 5, 3 to 7 and 5 to 9 can be neglected.
So we are looking for the least common multiple of the ending digits.
For 2 to 6 it would be 60, but 60 is no possible sum, the next one is 120. 120 is the sum of 22,23,24,25,26.
For 4 to 8 the least common multiple is 840, that is also no possible sum, so the first one in here is 1680.
So the solution is 22,23,24,25,26!