Answer:

11

Step-by-step explanation:

Average:-

The third number is 11

Hope it helps you!

Step-by-step explanation:

Given average = 12

Two numbers = 15 and 10

Let the third number be x

Average = Sum of values / Number of values

Average= (15+10+x) / 3

12 = ( 25 + x ) / 3

12 X 3 = 25 + x

36 = 25 + x

x = 36 - 25

x = 11