The sum of three numbers is 360 . If the ratio between the first and second be 3 : 4 and that of between the second and third be 4 : 5, then find the second number.

120

   I     :      II      :      III      :    Total

   3    :       4

                 4      :        5  

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  3     :       4      :        5     :     12

12R = 360

1R = 30 

4R = 4 × 30 = 120