2.45kg
First you calculate the price per kg as follows:
If it’s $20 for 12.25 kg, the price per kg is $20/12.25=$1.63 per kg
If you have $4, you can figure out what weight you can get by taking $4/the price per kg, so $4/$1.63, which is 2.45 kg.
The correct answer for this question is 68.
You cant simplify that fraction