New SAT Math Workbook

The computational processes are exactly the same just

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Unformatted text preview: he pay if he uses the car for 5 days and drives 1000 miles? (A) 5D + 1000c (B) (C) (D) (E) c 5D + 1000 10. The sales tax in Morgan County is m%. Represent the total cost of an article priced at $D. (A) D + mD (B) D + 100mD (C) (D) (E) D+ mD 100 m D+ 100 D + 100m 5D + 100c 5D + 10c 5D + c www.petersons.com Literal Expressions 135 1. COMMUNICATING WITH LETTERS Many students who have no trouble computing with numbers panic at the sight of letters. If you understand the concepts of a problem in which numbers are given, you simply need to apply the same concepts to letters. The computational processes are exactly the same. Just figure out what you would do if you had numbers and do exactly the same thing with the given letters. Example: Express the number of inches in y yards, f feet, and i inches. Solution: We must change everything to inches and add. Since a yard contains 36 inches, y yards will contain 36y inches. Since a foot contains 12 inches, f feet will contain 12f inches. The total number of inches is 36y + 12f + i. Example: Find the number of cents in 2x – 1 dimes. Solution: To change dimes to cents we must multiply by 10. Think that 7 dimes would be 7 times 10 or 70 cents. Therefore the number of cents in 2x – 1 dimes is 10(2x – 1) or 20x – 10. Example: Find the total cost of sending a telegram of w words if the charge is c cents for the first 15 words and d cents for each additional word, if w is greater than 15. Solution: To the basic charge of c cents, we must add d for each word over 15. Therefore, we add d for (w – 15) words. The total charge is c + d(w – 15) or c + dw – 15d. Example: Kevin bought d dozen apples at c cents per apple and had 20 cents left. Represent the number of cents he had before this purchase. Solution: In d dozen, there are 12d apples. 12d apples at c cents each cost 12dc cents. Adding this to the 20 cents he has left, we find he started with 12dc + 20 cents. www.petersons.com 136 Chapter 9 Exercise 1 Work out each problem. Circle the letter that...
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