Alright, lets get started.
Suppose Cary's current age = x
Suppose Dan's current age = y
Cary is 9 years older than Dan (given in question), means :
...............................equation (1)
After 10 years Cary's age = (x+10)
After 10 years Dan's age = (y+10)
In 10 years the sum of their ages will be 81, means


Subtrating 20 in both sides

.................................... equation (2)
From equation (1), putting the value of x in equation (2)


Subtrating 9 in both sides


Dividing by 2 in both sides




It means Cary's age is 35 and Dan's age is 26. : Answer
Hope it will help :)