SOLUTION: The total annual sales of a book in either paper or electronic form are 3500. Each paper
copy of the book costs $30 and each e-book costs $25. The total cost is $97 500.
(a) If
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-> SOLUTION: The total annual sales of a book in either paper or electronic form are 3500. Each paper
copy of the book costs $30 and each e-book costs $25. The total cost is $97 500.
(a) If
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Question 1172716: The total annual sales of a book in either paper or electronic form are 3500. Each paper
copy of the book costs $30 and each e-book costs $25. The total cost is $97 500.
(a) If x and y denote the number of copies in paper and electronic form, write down a pair of
simultaneous equations.
(b) Solve the equations to find the number of e-books sold. Answer by ikleyn(52788) (Show Source):
(a) A pair of simultaneous equations is
x + y = 3500 (1) (counting the books)
30x + 25y = 97500 (2) (counting dollars)
Writing these equations is absolutely standard and routine step,
it does not requires any explanations, because everything is clear and obvious as is.
(b) To find the number of e-books y, express x = 3500-y from equation (1)
and substitute it into equation (2). You will get single equation for y
30*(3500-y) + 25y = 97500
and from this equation y = = 1500.
ANSWER. 1500 e-books were sold.
Solved.
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This problem is of the same type as the classic tickets problems.
