Not really D:
When understood, it was quite easy. Now the other one ò.ò

working on it xD used the same sheet at first and wondered why are there 4 pairs that create the same sum, until i read that i need to add three numbers. dang! xD

"Seems I missed the fact that puzzle number 2 has three solutions"

I'm lazy lol.

It isn't so simple as 14x13x12, because I'm assuming you cannot re-use the same value for another sum
e.g. 146 + 139 + 223 AND 223 + 101 + 184 (223 is the re-used value)
because that means every value will be removed (this rule also applies to this puzzle anyway)

and I'm also assuming that once you find a value, you cannot use it for other sums:
e.g. 13 + 90 + 224 AND 98 + 146 + 83
and 13 + 104 + 184 AND 98 + 102 + 101 (13 and 98 are reused in other sums in this case)
because if you do so, you'll have less than 5 values left

:X I misunderstood the question.