Algebra

 

Real numbers a and b satisfy    
a + ab = 250    
a - ab = -240    
Enter all possible values of a, separated by commas.    

 

a + ab  =   250    

a – ab  = –240    

 

Just add the two equations     a + ab  =   250    

                                               a – ab  = –240    

                                             2a          =     10    

 

                                                        a  =  5    

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