Md 86t. Make sure you pick up the correet exam. digits unless specified otherwis

Question

Md 86t. Make sure you pick up the correet exam. digits unless specified otherwise. No exams will be accepted after Priday October 13, 2017 ase write your answers and work (if possible) on the exam sheet Pase label all your answers. You may use the last pag, for orate You will only receive credit for the original exam (or complete photocopy). You may use Mathematica , Maple or Excel unless otherwi 5 Q45 Linear Equations Homework and page 480 Solve following word problenm of the stamps are 49 ¢ stamps and some are 33 c stamps. How many 49 a. A customers walks into a post office to purchase stamps. She purchases a total of 54 stamps. Some e stamps and how many 33 e stamps did she purchase if the total cost of all the stamps was S 22.14 (8 points)

Explanation / Answer

Let the number of 49 cents and 33 cents stamps purchased by the customer be x and y respectively. Then x+y = 54…(1). Also, since the total value of the stamps is $ 22.14, we have 0.49x +0.33y = 22.14 or, on multiplying both the sides by 100, we have 49x+33y = 2214…(2). Now on multiplying both the sides of the 1st equation by 33, and then on subtracting the result from the 2nd equation, we have 49x+33y -33x-33y = 2214 -54*33 or, 16x = 2214 -1782 = 432 so that x = 432/16 = 27. Further, on substituting x = 27 in the 1st equation, we get 27+y = 54 so that y = 54-27 = 27. Thus, the customer purchased 27 stamps of 49 cents and 27 stamps of 33 cents.

Note:

Since 27*49 + 27 *33 = 1323+891 = 2214, our answer is correct.

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