One milliliter is equivalent to one centimeter cubed. Therefore,
7,120 mL = 7,120 cm³
One decimeter is equal to ten centimeters,
1 dm = 10 cm
Cubing both sides,
1 dm³ = 1000 cm³
x dm³ = 7,120 cm³
Cross multiplying and solving for x, we get
7.12 dm³ = 7,120 mL