# Math Textbooks for Sale

Pro Problems > Math > Algebra > Equations > Systems of Equations > Word Problems## Math Textbooks for Sale

The cost of a textbook is directly proportional to the number of math problems it contains, and inversely proportional to the number of authors who wrote the book. A textbook which contains 200 problems, and was written by 3 authors costs $5 less than a textbook which contains 150 problems, and was written by 2 authors. What is the cost of a textbook containing 450 problems, and written by 4 authors?

## Solution

In order to make it feasible for teachers to use these problems in their classwork, no solutions are publicly visible, so students cannot simply look up the answers. If you would like to view the solutions to these problems, you must have a Virtual Classroom subscription.## Similar Problems

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One king's horse can break a piece in two every 2 seconds.

There are twenty more men than horses.

If there had been six fewer men, and horses broke pieces at a rate of one every three seconds, they could have done the job.

If the number of men and the number of horses are both prime numbers, how many men and horses are there?

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Find all four integers.

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The sum of two numbers is eleven less than four times the smaller number. The difference between the numbers is five more than the smaller number. What is the larger number?