Question

The puzzle contains the numbers 21-29. Each column and each row add up to the number given outside the boxes. Put the correct number in each box to complete the addition equations without repeating any numbers.

What is the value of X?

Answer 1

27 + 21 + a = 72
a = 72 - 21 - 27
a = 24

24 + 25 + b = 78
b = 78 - 24 - 25
b = 29

29 + 28 + X = 80
X = 80 - 29 - 28
X = 23

Thus, X = 23