Question

if the weight of 8 ion balls is 128 kgthen the weight of 3 such iron ball will be

Answer 1

Weight of 8 iron balls= 128 kg
Weight of 1 iron ball= 128/8 kg
Weight of 3 iron balls= 128/8 x 3
=48 kg

Answer 2

Here is your answer mate:
The wiegth of one ball=128/8=16kg.
Now the weight of 3 balls=16×3=48kg.
Hope it helps you.