Answer:
10 ml of a 72% solution, 20 ml of a 54% solution
Step-by-step explanation:
x ml - amount of a 72% solution
y ml - amount of a 54% solution
[tex]\left \{ {{x+y=30} \atop {72x+54y=30*60}} \right.[/tex]
[tex]\left \{ {{x=30-y} \atop {72(30-y)+54y=1800}} \right.[/tex](1)
(1) 2160-72y+54y=1800
y=20
x=30-y=30-20=10