Answer: See explanation
Explanation:
From the question, we are informed that the weight of 90 books is 50kg. We need to get the weight of a book first and this will be:
= 50/90
= 5/9
Therefore, the weight of 180 such books will be 5/9 multiplied by 180. This will be:
= 5/9 × 180
= 100kg