Hi
Ryan had $120 more than Kaden. Kaden had 1/4 as much as Ryan. Both of them spent a total of $170. As a result Kaden had 2/3 as much as Ryan. 
A) how much did they have altogether in the end. 
B) how much did Kaden have in the end.

Let original amount Kaden had, be K
Ryan had $120 more than Kaden. so original amount Ryan had, was K + 120
Also, Kaden had  as much as Ryan, so original amount Ryan had, was 4K
             We now get: K + 120 = 4K
                             120 = 4K - K
                             120 = 3K
Original amount Kaden had, or 
Original amount Ryan had: 40 + 120, or 4(40) = $160

Total amount they had, originally: $40 + $160 = $200
Since they spent a total of $170, remainder was $200 - 170 = $30


Let Kaden's remainder be Kr 
Since in the end, Kaden had  as much as Ryan, then Ryan's remainder was  of Kaden's, or 
With total remainder being $30 (see above), we get:  
                                                       ------ Multiplying by LCD, 2
                                                            
                                  Kaden's remainder, or