Answer:
The correct answer is Jacob bought 2 adult tickets and 7 children tickets or 7 adult and 2 children tickets.
Explanation:
Total number of concert tickets Jacob had to buy is 9.
Cost of each adult ticket is $10.
Total amount of money spent by Jacob $76.
Let Jacob buy x adult tickets and y children tickets and $K be the price of the children tickets where K is a positive integer.
Therefore 10x + Ky = 76 and x + y = 9.
Let x = 7 then y = 2 at K = $3.
Let x = 6 then Ky = 16 cannot satisfy all the conditions.
Let x = 5 then Ky = 26 cannot satisfy all the conditions.
Let x = 4 then Ky = 36 cannot satisfy all the conditions.
Let x = 3 then Ky = 46 cannot satisfy all the conditions.
Let x = 2 then y = 7 at K = $8.
Let x = 1 then Ky = 66 cannot satisfy all the conditions.
Thus Jacob has either bought either 7 adult and 2 children tickets or 7 children tickets and 2 adult tickets.