Chris, Alex and Jesse are all siblings in the same family. Alex is 5 years older than chris. Jesse i

Discussion in 'Calculator Requests' started by math_celebrity, Jan 8, 2017.

  1. math_celebrity

    math_celebrity Administrator Staff Member

    Chris, Alex and Jesse are all siblings in the same family. Alex is 5 years older than chris. Jesse is 6 years older than Alex. The sum of their ages is 31 years. How old is each one of them?

    Set up the relational equations where a = Alex's age, c = Chris's aged and j = Jesse's age
    1. a = c + 5
    2. j = a + 6
    3. a + c + j = 31
    4. Rearrange (1) in terms of c: c = a - 5


    Plug in (4) and (2) into (3)
    a + (a - 5) + (a + 6) = 31

    Combine like terms:
    3a + 1 = 31

    Subtract 1 from each side
    3a = 30

    Divide each side by 3
    a = 10

    Plug in 1 = 10 into Equation (4)
    c = 10 - 5
    c = 5

    Now plug 1 = 10 into equation (2)
    j = 10 + 6
    j = 16
     

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