Answer:
36
Step-by-step explanation:
Because the sum of 2 number is 9 so we have all posible number with sum is 9:
18, 27, 36, 45, 54, 63, 72, 81, 90
When we intercharge it, it become 27 greater than the original number, so that number would be:
18 => 81 (63 greater) wrong
27 => 72 (45 greater) wrong
36 => 63 (27 greater) right
So 36 would be the number that you are looking for!
Hope this helped you :3