a= cantitatea in prima zi
4a/9 a mai ramas
a-4a/9=5a/9
( 5a/9)·2/5=10a/45=2a/9⇒a II azi
5a/9-2a/9=3a/9 a mai ramas
(3a/9)·2/4=6a/36=a/6⇒ a III a zi ⇒a mai ramas 1125kg
a=4a/9+2a/9+a/6+1125
a=(8a+4a+3a+18·1125)/18
18a=15a+18·1125
3a=18·1125
a=6·1125=6750kg cantitatea initiala in depozit