How do I filter the data downwards?

Question

I’m trying to filter the data from a table I have on SQL from the highest value to the lowest, but I’m not getting anywhere with Mysql.

Source code below

select max(id_nf), min(quantidade * valor_unit) AS VALOR_TOTAL from objects, 

Exercise below:

Search the total value of NF and sort the result of the highest value to the lowest. The columns present in the query result are: ID_NF, VALOR_TOTAL.

Remark: THE VALOR_TOTAL is obtained by the formula: ∑ QUANTIDADE * VALOR_UNIT.

Answer 1

I think what the exercise calls for is a sum of the total amount that would be :

select id_nf,sum(quantidade * valor_unit) as valor_total 
from objects 
group by id_nf 
order by 2 desc