theo bài ra ta có:
dầu cá= 1/2 thân +500g x 1/2 = 1/2 than +250g
than ca =1/2 than +250g +500g =1/2 than + 750g
\(\Rightarrow\)1/2 than ca = 750 g
\(\Rightarrow\)than ca=750.2=1500g
\(\Rightarrow\)dau ca=750g+250g=1000g
\(\Rightarrow\)con cá nặng 1000+1500+500=3000g
ta co 3000g=3kg
vậy con cá nặng 3kg