Question

the average of 25 results is 18 that is 18 , that of first 12 is 14 and of the last 12 is 17 thirteenth results is

Answer 1

$25 \times 18 = 450 \\ 12 \times 14 = 168 \\ 12 \times 17 = 204 \\ 168 + 204 = 372 \\ 450 - 372 = 78$