How much would you go up or down if the road stayed at 8% for one mile?

In a school 2/3 of the students study a language of those who study a language 2/5 study french

Which geometric principle is used to justify the construction below?

Ateacher wanted to buy a chair, a bookshelf, two tables and a desk. she spent $900 for all five items and the chair and the desk combined 70% of her total. if the bookshelf cost $50, how much did each of the tables cost?