The average of a, b and c is 19, and the average of b, c and d is 16. If $a = 26$, what is d?

Explanation

1. 01

   $a + b + c = 3 \times 19 = 57$ and $b + c + d = 3 \times 16 = 48$.

2. 02

   Subtracting: $a - d = 57 - 48 = 9$.

3. 03

   $d = 26 - 9 = 17$.