If all etching were sold at $35 each, the total cost would have been $ 560, that is $45 less than the actual cost. Since each $40 etching sold increased the cost by $5, there were 45/5= 9 etchings at $40 and 16-9= 7 etchings at $35.

Answer: 7 etchings were sold at $35 and 9 etchings were sold at $40.