51
-13
Add up all the numbers and divide that total by the number of numbers. 1+ 2 + 3 + 4 + 5 = 15 15/5 = 3 The average is 3
27
26
15
45
51
The numbers are: 12 and -15
They all relate by adding up the 6+6+3=15 You can not get to the sum of 15 is you don't have the first 3 numbers to add up.
-13
There is no answer to this. The factors of 15 are 1, 3, 5 and 15. The only numbers that add up to four are 1+3, 4+0 and 2+2.
Add up all the numbers and divide that total by the number of numbers. 1+ 2 + 3 + 4 + 5 = 15 15/5 = 3 The average is 3
-15
1+2+3+4+5
Add all of the numbers up, and then divide that result by how many numbers there were, e.g. 1,2,3,4,5. Added up they make 15. As there are five numbers there, you divide 15 by 5, and you get 3. Voila.
-23