SOLUTION
Given the question in the image, the following are the solution steps to answer the question.
STEP 1: Write the given details
Total rice bought is 75kg
Each week, he used 4.5kg, this means in w weeks, he will use:

STEP 2: Get the remaining kilograms of rice after w weeks
This will be gotten by using the function below:

Hence, the function will be gotten as:
