There are infinitely many possible answers.
Start with the first number as 1.
1+5+6, 1+4+7, 1+3+8, 1+2+9, 1+1+10, 1+0+11, 1-1+12, 1-2+13 etc
then include numbers with 1 decimal point (dp)
1+5.1+5.9, 1+4.1+6.9, 1+2.1+8.9, etc
then 2 dp
1+5.01+5.99, and so on
and then 3 dp, 4 dp, and on to infinitely many decimal points.
All along, the first number has been 1. That number can now be varied: it can take infinitely many values and with each of its values, there are an infinite number of possibilities for the other two.
All in all, there is no simple answer to the question.
11 x 12 x 13 = 1716
The sum of the first three even positive integers is 2 + 4 + 6 = 12.
55
One way to do it is to look at each of the three as a part of the total. So you can consider the ratio 2:3:7 as the first thing being 2/12 of the total, the second being 3/12 and the third being 7/12.
There are no three consecutive numbers with a sum of 170.
11, 12, and 13
The mean times three will be the total of all three numbers. Multiply the mean times three and subtract the sum of the two numbers from that total.
12
3 and 12
The average of these three numbers is 12.
The numbers are 110, 111 and 112.
12 and any three multiples of 12.