# Using the following ages   Debbie 56    Jennifer 16    Eddie 60 How old was Eddie when Debbie was born? Write an equation that shows how old in years each of you will be, when your ages...

Using the following ages   Debbie 56    Jennifer 16    Eddie 60

How old was Eddie when Debbie was born?

Write an equation that shows how old in years each of you will be, when your ages add up to 150 years old.  Explain the reasoning which helped you develop your equation.  Solve for your future ages.  Are your answers reasonable, do they add up to 150?  In years. how old was Debbie when the youngest person was born?  Write an equation which models how old in years each of you will be when Debbie is three times as old as the younger person.  Explain how you develop your equation.  Solve the equation of your ages when  Debbie  is three times as old as the youngest person.  Are the answers reasonable?

rcmath | High School Teacher | (Level 1) Associate Educator

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Part 1: Eddie Age when Debbie was born: 4

For sake of simplicity, I will be using d as Debbie age, j as jennifer age, and e as Eddie's.

Part 2: Ages add up to 150
d+j+e=150
notice that d=j+40 and e=j+44. I opted to write everyone's age in term of j, because she is the youngest.
Then we have the following:

d+j+e=150 =>
j+40+j+j+44=150 =>
3j+84=150 =>
3j=66 =>
j=22

Thus Jennifer is 22, Debbie is 62, and Eddie is 66.

Part 3: Debbie was 40 when Jennifer was born.

Part 4: d=3j
We also know that d=j+40, so we solve the system of linear equations. I am going to use the substitution method.
3j=j+40 =>
2j=40 =>
j=20

Thus Jennifer is 20, Debbie is 60, and Eddie is 64.