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She earns \$20$20dollar sign, 20 per hour as a carpenter and \$25$25dollar sign, 25 per hour as a blacksmith. Last week, Giselle worked both jobs for a total of 303030 hours, and earned a total of \$690$690dollar sign, 690.

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Answer:

  • Carpentry = 12 hours
  • Blacksmithing = 18 hours

Step-by-step explanation:

Question wants to know the number of hours se worked at each.

This is a simultaneous equation problem.

Assume the carpenter job is x and the blacksmith is y.

x + y = 30

20x + 25y = 690

Substitution:

x + y = 30

y = 30 - x

20x + 25y = 690

20x + 25(30 - x) = 690

20x + 750 - 25x = 690

-5x = 690 - 750

-5x = -60

x = -60/-5

= 12 hours for carpentry

y = 30 - x

= 30 - 12

= 18 hours for blacksmithing

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