h
Vol = 3² · h = 9 ·h
9· h dm³ = 9·h dm² = 18 dm³
h = 18:9 = 2dm
2 . cubul are Vol =3³dm³ = 27 dm³
27 dm³ - 18 dm³ = 7 dm³ = 7 litri lipsesc
c. o fata a cubului are nevoie de 3² dm² = 9dm² sticla
acvariu = 5·9 dm² =45 dm² = 0,45 m² sticla