The cost of $3kg$of rice is$₹120$. What will be the cost of $8kg$of rice $?$

The cost of $3kg$ of rice$=₹120$

The cost of $1kg$of rice$=\frac{120}{3}$

$=₹40$

The cost of $8kg$of rice $=8\times 40$

$=₹320$

Hence, the cost of $8kg$of rice is $₹320$.