tolong di bantu yaa, kalau bisa pakai cara gak papa

rho air=1 g/cm kubik
Vb=V'+V"
2000=V'+V"

rho air * V"=rho benda*Vb
1*V"=0,8*2000
V"=1600 cm kubik

2000=V'+V"
2000=V'+1600
V'=400 cm kubik (A)