The correct answer for the question shown above is: Gabriel should use 2 kilograms of compost.
The explanation is shown below:
1. To solve the exercise you must apply the following proccedure:
2. You have that He wants it to be 2 parts compost to 10 parts potting soil and he wants to end up with 10 grams of mix. Therefore:
=(2/12)x12 kilograms
=0.166x12 kilograms
=2 kilograms