algebra

 

If I give my brother 5 dollars, then we will have the same amount of money. If instead he gives me 25 dollars, then I'll have twice as much money as he will have. How much money does my brother currently have (in dollars)?  

 

Let M stand for My original amount  

Let B stand for Brother's original amount   

 

                                                             (M – 5)  =  (B + 5)   

                                                             (M + 25)  =  (2)(B – 25)  

 

                                                              M – 5  =  B + 5   gives us  M = B + 10    (1)  

 

                                                              M + 25  =  2B – 50                                 (2)  

 

Substitute the value of M from (1)   

into the equation (2)                             B + 10 + 25  =  2B – 50   

 

Combine like terms                                          85  =  B    

 

                                                   Brother has 85 dollars .   

 

The problem doesn't ask for My original amount but it's B + 10 = 95  

 

Check answer  

 

If I give my brother 5, then I'll have 90 and so will he, so we have the same.  

If my brother gives me 25, then I'll have 120 and my brother will have 60.  

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