Question 1142811
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12 years old Umar is three times as old as his brother Ali.How old will Umar be when he is twice as old as Ali?
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U, 12
Ali, A

{{{12=3A}}}

{{{A=4}}}


So the starting information is  {{{system(U=12,A=4)}}}.  You should be able to continue toward the question on your own.  Say, in x more years, Umar will be 12+x and Ali will be 4+x.   Take it from here.