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5 minutes. Warm-Up. Beth and Chris drove a total of 233 miles in 5.6 hours. Beth drove the first part of the trip and averaged 45 miles per hour. Chris drove the second part of the trip and averaged 35 miles per hour. For what length of the time did Beth drive?. 8.6 Digit and Coin Problems.
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5 minutes Warm-Up Beth and Chris drove a total of 233 miles in 5.6 hours. Beth drove the first part of the trip and averaged 45 miles per hour. Chris drove the second part of the trip and averaged 35 miles per hour. For what length of the time did Beth drive?
8.6 Digit and Coin Problems Objectives: To use systems of equations to solve digit and coin problems
Example 1 The sum of the digits of a two-digit number is 10. If the digits are reversed, the new number is 36 less than the original number. Find the original number. Let x = the tens digit Let y = the ones digit 2x - 4= 10 x + y = 10 10y + x = 10x + y - 36 2x= 14 x= 7 9y = 9x - 36 y = x - 4 y = x - 4 x + y = 10 y = 7 - 4 x +(x – 4)= 10 y = 3 73 2x - 4= 10
Practice The sum of the digits of a two-digit number is 5. If the digits are reversed, the new number is 27 more than the original number. Find the original number.
Example 2 A collection of nickels and dimes is worth $3.95. There are 8 more dimes than nickels. How many dimes and how many nickels are there? Let n be the number of nickels. Let d be the number of dimes. 0.05n + 0.10d = 3.95 d = 8 + n d = 8 + n 0.05n + 0.10(8 + n) = 3.95 d = 8 + 21 0.05n + 0.80 + 0.10n = 3.95 d = 29 5n + 80 + 10n = 395 21 nickels 80 + 15n = 395 29 dimes 15n = 315 n = 21
Practice Rob has $2.85 in nickels and dimes. He has twelve more nickels than dimes. How many of each coin does he have?
Example 3 There were 166 paid admissions to a game. The price was $2 for adults and $0.75 for children. The amount taken in was $293.25. How many adults and how many children attended? Let a be the number of adults who attended Let c be the number of children who attended a + c = 166 2a + 0.75c = 293.25 a + c = 166 a = 166 - c a + c = 166 2(166 – c)+ 0.75c = 293.25 a + 31 = 166 332 – 2c + 0.75c = 293.25 a = 135 332 - 1.25c = 293.25 135 adults - 1.25c = -38.75 c = 31 31 children
Practice The attendance at a school concert was 578. Admission cost $2 for adults and $1.50 for children. The receipts totaled $985.00. How many adults and how many children attended the concert?
Homework study guide