Shiloh is 7 years older than Courtney. Shiloh's age is 13 years less than two times Courtney's age. The system below models the relationship between Shiloh's age (s) and Courtney's age (c) : s = c + 7 s = 2c - 13 Which of the following methods is correct to find Shiloh's and Courtney's age?

I'm afraid I don't see the models you have written about although I do know the answer. (C = Courtney's age, S = Shilo's age)

Shilo is 7 years older then Courtney, which equals to C+7=S.

While at the same time Shilo is 13 years younger then twice Courtney's age. This turns into Cx2-13=S.

c+7=cx2-13. This is the equation, now lets work it out.

Add 13 on each side and you get

c+20=2c

Now we subtract c from each side and we get

20=c Therefor we have found out that Courtney is 20 years old.

Shilo being 7 years older then Courtney is 27