Errata....

I wrote:
Dipwind wrote:
if the supplier sends less amount than the request
" C5=15000; D5=13000 " I obtain the result in E5 of 115%.
when actually the efficiency against my request was 85%.
[....]
In the example above, 13000 is 85% of 15000, but
it is 13% less than 15000.

I parroted the OP's mistake without thinking. Actually, 13000 is 87%
of 15000.