Given:
I'm 3 times younger than my mom but 3 times older than my younger brother.
Mom is older than my younger brother by 40 years.
To find:
How old am I.
Solution:
Let x be the age of the younger brother.
I'm 3 times older than my younger brother. So, my age is 3x.
I'm 3 times younger than my mom. So, she is 3 times older than me and her are is 3(3x)=9x.
The difference between the age mother and younger brother is 40 years.
[tex]9x-x=40[/tex]
[tex]8x=40[/tex]
Divide both sides by 8.
[tex]x=\dfrac{40}{8}[/tex]
[tex]x=5[/tex]
Now,
My age [tex]=3x[/tex]
[tex]=3(5)[/tex]
[tex]=15[/tex]
Therefore, I'm 15 years old.
