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Of the three numbers, the sum of the first two is 45; the sum of the second and

  1. Iamsam profile image80
    Iamsamposted 5 years ago

    Of the three numbers, the sum of the first two is 45; the sum of the second and third is 55 and...

    Of the three numbers, the sum of the first two is 45; the sum of the second and third is 55 and
    the sum of the third and thrice the first is 90. The third number is :


    Options (1) 20                 (2) 25                    (3) 30                 (4) 3

  2. wqaindia profile image81
    wqaindiaposted 5 years ago

    My head says it is 30. The three numbers will be 20, 25 and 30 . 20+25=45, 25+30=55, 30+20*3=90. All is well that ends well.

  3. drpennypincher profile image94
    drpennypincherposted 5 years ago

    (3) 30

    Let a represent the first number, b the second, and c the third

    Eq 1 a+b=45
    Eq 2 b+c=55
    Eq 3 3a+c=90

    Solve Eq 1 for b: b=45-a
    Substitute this into Eq 2: (45-a)+c=55
    Simplify: c=10+a
    Substitute into Eqn 3: 3a+(10+a)=90
    Solve: a=20
    Substitute a=20 into Eqn 3:
    3(20)+c=90
    Solve: c=30

  4. joanwz profile image75
    joanwzposted 5 years ago

    The answers are:
    A = 20
    B = 25
    C = 30

    a+b = 20+25 = 45
    b+c = 25 +30 = 55
    c+3(a) = 30 + (3x20) = 30 +60 = 90

    1. Iamsam profile image80
      Iamsamposted 5 years agoin reply to this

      Well done.  Thanks for solving the problem

 
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