Answer is 9

1st triangle: 7-4+9=12 2nd triangle: 1-1+4=4 3rd triangle: 6-2+5=9.

there is no mathematics is required for this.... 9 + 7 - 4 = 12 4 + 1 - 1 = 4 5 + 6 - 2 = 9 So the answer is 9..

Which number should replace the question mark?

Which number should replace the question mark in the picture below ?

5 12 15 7 9 4 23 87 ?