Let's call x the age of Cary and y the age of Dan.
y = x - 55
x + 5 + y + 5 = 81
Then,
x + 5 + x - 55 + 5 = 81
2x - 45 = 81
2x = 81 + 45
2x = 126
x = 126/2 = 63
Now, let's find y.
y = 63 - 55 = 8.
Therefore Cary is 63 years old and Dan is 8 years old.
Hope this helps !
Photon