Alice is 3 years younger than Barbara, and Barbara is 5 years younger than Carol. Together the siste

Discussion in 'Calculator Requests' started by math_celebrity, Aug 14, 2018.

  1. math_celebrity

    math_celebrity Administrator Staff Member

    Alice is 3 years younger than Barbara, and Barbara is 5 years younger than Carol. Together the sisters are 68 years old. How old is Barbara?

    Let a be Alice's age, b be Barbara's age, and c be Carol's age. We have 3 given equations:
    1. a = b - 3
    2. b = c - 5
    3. a + b + c = 68
    Rearrange (2)
    c = b + 5

    Now plug in (1) and (2) revised into (3). We want to isolate for b.
    a + b + c = 68
    (b - 3) + b + (b + 5) = 68

    Combine like terms:
    (b + b + b) + (5 - 3) = 68
    3b + 2 = 68

    Run this through our equation calculator, and we get b = 22
     

Share This Page