Translation:If I could, I would have given more money.
DL's translation is valid. There are (1) hypothetical statements focused entirely on the present: "present condition" with "present result"; (2) there are hypothetical statements that focus only on the past: "past condition" and "past result". (3) There are also mixed conditionals as in DL's example.
"If I could/were able, I would have given more money." A lack of money is a long-term condition. It affects the past as well as the present.
Another example: If Bill's family weren't so poor, he would have finished his education.
Third section on the list.
Exactly! I wrote the same comment when this sentence came up on a different exercise- I agree. Indeed, I believe (though I am not positive) that it should be similar em português: "Se eu pudesse, daria mais dinheiro" VS. "Se eu tivesse podido, teria dado mais dinheiro." I don't think I ever got a response to my other comment...
I think DL is confused in this part. I wrote, "If I had been able, I would have given..." but DL didn't like it and told me I should have written, "If I were able to, I would have given..." which is just wrong. You would say, "If I were able, I would give;;;". To go with "would have given" you need "had been able".
DL's sentence is an example of a mixed conditional: present in the "if" clause, past in the result clause. See the third section on the list: