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The Johnson boys were born two years after their older sister. Let s represent the age of the older sister.
a. Write an expression, in terms of s, for the sum of the twins and their sister.
b. Write an expression, in terms of s, for the product of ages of the twins and their sister.
c. This year, the product of the three siblings ages is exactly 8 more than the sum of their ages. Write an equation, in terms of s, to represent this fact.
d. What are the ages of the twins and their sister? Show or explain how you got your answer.
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If s represents the age of the older sister, then the age of twins is s-2 of each.
a. The sum of the twins' ages and their sister's age is 2*(s-2) + s.
b. The product of ages of the twins and their sister is .
c. The equation is = 2*(s-2) + s + 8.
d. Now simplify and solve this equation:
= ,
= ,
= .
Group the terms
= ,
= ,
= .
The solution is s = 4.
Answer. The ages of the twins are 2 years each and the age of the sister is 4 years.