+13 Étienne and Hans were collecting vintage stamps. Étienne gave 1/4 of his stamps to Hans. Hans then gave 1/3 of his total stamps to Étienne. After these exchanges, Étienne had 4 times as many stamps as Hans. If the number of stamps Étienne gave to Hans was 10 more than the number of stamps Hans gave back to Étienne, how many stamps did Hans have at first?
