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8th grade

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how do you solve c=3d-27 ; 4d+10c=120

  • 8th grade -

    (1) c = 3d - 27
    (2) 4d + 10c = 120
    there are several ways to solve this problem (system of linear equations),, but in this case, we substitution method since in equation (1), variable c is expressed in terms of the other variable d,, we then substitute c from equation (1) to equation (2):
    4d + 10(3d-27) = 120
    4d + 30d - 270 = 120
    34d = 390
    d = 195/17

    *substituting this value of d to either equations (in this case, to (1)):
    c = 3d - 27
    c = 3(195/17) - 27
    c = 585/17 - 27
    c = (585 - 459)/17
    c = 126/17

    so there,, :)

  • 8th grade Math -

    How do you solve this problem? V = Bh

    Solve each formula for the variable shown in RED. In this problem the variable in RED is the letter B.

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