Which number should replace the question mark?
5 12 15 7 9 4 23 87 ?
The answer is 41 EXPLANATION: Each number in the third row is the difference of the product and sum of the numbers in the same column of the first and second rows. C=A×B−(A+B) 5×7−(5+7)=35−12=23 12×9−(12+9)=108−21=87 15×4−(15+4)=60−19=41
Which number should replace the question mark in the picture below ?