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Math Help - Solving applications: Systems of three Equations

  1. #1
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    Solving applications: Systems of three Equations

    I have this word problem that i am having trouble on i am usually good with word problems but my instructor has completely caught me off guard with this one:

    The problem is:
    The sum of three numbers is 85. The second is 7 more than the first. The third is 2 more than four times the second. Find the numbers.

    So far what i have is:

    Let x = the first number
    let y = the second number
    let z = the third number

    x+y+z=85
    y=2+x
    Z=2+4y

    This is where i am stuck. I have read the chapter multiple times and have yet to come up with the correct answer. Am i writing the correct equations for the problem given? If so, what step should i take about solving this? Please help thanks in advanced.
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  2. #2
    MHF Contributor harish21's Avatar
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    Quote Originally Posted by wcruz1 View Post
    I have this word problem that i am having trouble on i am usually good with word problems but my instructor has completely caught me off guard with this one:

    The problem is:
    The sum of three numbers is 85. The second is 7 more than the first. The third is 2 more than four times the second. Find the numbers.

    So far what i have is:

    Let x = the first number
    let y = the second number
    let z = the third number

    x+y+z=85
    y=2+x The second number is 7 more than the first!!
    Z=2+4y

    This is where i am stuck. I have read the chapter multiple times and have yet to come up with the correct answer. Am i writing the correct equations for the problem given? If so, what step should i take about solving this? Please help thanks in advanced.




    The sum of three numbers is 85 .
    So x+y+z=85.....(I)

    The second is 7 more than the first
    so, y = x+7....(II)

    The third is 2 more than four times the second
    s0, z = 2+4y....(III)

    substitute (II) and (III) in (I) and find x,y, and z

    So, x+y+z=85

    or, x+(x+7)+(2+4y)=85

    or, x+(x+7)+(2+4(x+7))=85
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  3. #3
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    okay got it thanks for your help 8,15,62 this just made life like a million times easier
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