Question 1204081
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The solution from tutor @mananth is a very inefficient solution using two variables, starting from the given information that the sum of their current ages is 35 years.<br>
"7 years ago one brother was twice the age of the other" gives us a much easier way to set up the problem for solving, using a single variable.<br>
Let x = age of younger brother 7 years ago
then 2x = age of older brother 7 years ago<br>
The difference in their ages at any time is the difference in their ages 7 years ago, which is 2x-x = x.<br>
The sum of their current ages is 35:<br>
(x+7)+(2x+7)=35
3x+14=35
3x=21
x=7<br>
ANSWER: the difference in their ages is 7 years -- i.e., they were born 7 years apart<br>