Question 1204081
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the combined age of 2 brothers is 35 years old. 7 years ago one brother was twice the age of the other. 
how many years apart were they born
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        Nice/ideal problem to solve it  MENTALLY,  without using equations.



<pre>
Seven years ago the combined age of the two brothers was 35 - 7 - 7 = 21 years.


In addition, we are given that 7 years ago (i.e., at that time), one brother was twice the age of the other.


It means (as anyone can get immediately), that 7 years ago the older brother was 14 years old,
while the younger brother was 7 years old at that time.


Hence, the brothers were born 14-7 = 7 years apart.
</pre>

Solved.


As clear as 2 - 1 = 1.


Compare with the solution by @mananth.