Answer:
7
Step-by-step explanation:
Given that there are 5 number cards.
They are 2,5,7,8,9
Total of all numbers in the cards = 2+5+7+8+9= 31
One card is removed say with number x.
Now sum new would be =31-x .. i
Average of remaining 4 cards = 6
So sum of remaining 4 cards = 6(4) = 24 ... ii
i and ii represent the sum of remaining 4 cards. Hence they should be equal
31-x =24
Subtract 31 from both sides to get
-x=-7
Or x =7
