SOLUTION: I am half the age of my dad plus four but I know that my dad is eight years older than my mum and my mum gave birth to me at the age of twenty eight. What is my age?
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Question 1063181: I am half the age of my dad plus four but I know that my dad is eight years older than my mum and my mum gave birth to me at the age of twenty eight. What is my age? Answer by ikleyn(52781) (Show Source):
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I am half the age of my dad plus four but I know that my dad is eight years older than my mum and my mum gave birth to me
at the age of twenty eight. What is my age?
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The first equation is
I = (1) (I is "my age", D is dad's age)
The second equation is
D - I = 28 + 8. (2) (My dad is 28+8 years older than me).
You can rewrite equations (1) and (2) in the form
2I = D + 8 (1')
D - I = 36. (2')
From (2'), express D = 36 + I and then substitute it into (1') replacing D. You will get
2I = (36+I) + 8 ----> 2I = I + 44 ----> I = 44.
