Question 227956
Paula is 12 years older than her brother Bob. Four years from now Bob will be two thirds as old as Paula. How old are they now?


Step 1.  Let x be the age of Bob


Step 2.  Let x+12 be the age of Paula since she's 12 years older than Bob.


Step 3.  Let x+4 be the age of Bob in four years.


Step 4.  Let x+12+4=x+16 be the age of Paula in four years.


Step 5.  Then, {{{x+4=2(x+16)/3}}} since in four years from now Bob will be two thirds as old as Paula.


Step 6.  Solving the equation in Step 5 {{{x+4=2(x+16)/3}}} yields the following steps


Multiply by 3 to both sides of the equation to get rid of the denominator.  


{{{3(x+4)=3*(2(x+16)/3)}}}


{{{3x+12=2x+32}}}


Subtract 2x+12 from both sides of the equation


{{{3x+12-(2x+12)=2x+32-(2x+12)}}}


{{{x=20}}}  and {{{x+12=32}}}


Check the solution {{{x=3}}} and substitute into original equation {{{x+4=2(x+16)/3}}} 


{{{20+4=2(20+16)/3}}}


{{{24=2(36)/3}}} 


{{{24=24}}} which is a true statement.


Step 7.  ANSWER:  Bob is 20 years old and Paula is 32 years old.


I hope the above steps were helpful.


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And good luck in your studies!


Respectfully,
Dr J

http://www.FreedomUniversity.TV