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anonymous

  • 5 years ago

the number of hours per week spent drinking exeeded the number of hours per week spent studying by 1.8 hours. if an average of 18.6 hours per week were spent on both activities, determine the average number of hours spent per week spent on each activities

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  1. sandra
    • 5 years ago
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    ok hmmm. I'm going to try to translate these into equations

  2. sandra
    • 5 years ago
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    so let's say time drinking is "d" and time studying is "s"

  3. sandra
    • 5 years ago
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    the first line means that d = s + 1.8

  4. sandra
    • 5 years ago
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    so if we know an average of 18.6 hours/week were spent on both activities, then that means that d+s/2 = 18.6

  5. sandra
    • 5 years ago
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    now you need to use substitution to get the final answer - i.e. take the value of a variable from one equation and substitute it into the other - since you need an equation to be all of one variable to solve it

  6. sandra
    • 5 years ago
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    in this case, how about we substitute d from the first equation (s+1.8), into the second

  7. sandra
    • 5 years ago
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    1. d = s + 1.8 2. (d+s)/2 = 18.6 3. (s+1.8 + s)/2 = 18.6 4. (2s + 1.8)/2 = 18.6 5. 2s + 1.8 = 37.2 6. 2s = 35.4 7. s = 17.7 17.7 hours were spent studying

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