Rule of three Khan Academy Talent Search 2015
Formula for solving simple rule of three problems.
Answer
Seven readers have 84 pages how many pages will 6 readers have?
To solve that we need to use the rule of three:
7 readers--- 84 pages
6 readers--- =??? pages
By using the rule of three we multiply: 6 x 84 and we divided by 7 :
6 x 84 / 7 =
$$6\times84\div7$$
Solution:
$$72$$
The numbers of pages that 6 readers will have: 72 pages.