Dennis was getting in shape for a marathon. The first day of the week he ran n miles. Dennis then ad

Discussion in 'Calculator Requests' started by math_celebrity, Jan 15, 2023.

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  1. math_celebrity

    math_celebrity Administrator Staff Member

    Dennis was getting in shape for a marathon. The first day of the week he ran n miles. Dennis then added a mile to his run each day. By the end of the week (7 days), he had run a total of 70 miles. How many miles did Dennis run the first day?

    Setup distance ran for the 7 days:
    1. n
    2. n + 1
    3. n + 2
    4. n + 3
    5. n + 4
    6. n + 5
    7. n + 6
    Add them all up:
    7n + 21 = 70

    Solve for n in the equation 7n + 21 = 70

    Step 1: Group constants:
    We need to group our constants 21 and 70. To do that, we subtract 21 from both sides
    7n + 21 - 21 = 70 - 21

    Step 2: Cancel 21 on the left side:
    7n = 49

    Step 3: Divide each side of the equation by 7
    7n/7 = 49/7

    n = 7

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