The sum of three numbers is 210. If the ratio between the first and second be 2 : 3 and that of between the second and third be 4 : 5, then find the second number.

72

   I     :      II      :      III      :    Total

   2    :       3

                 4      :        5  

-------------------------------------------------               

  8     :       12    :       15     :     35

35R = 210

1R = 6

12R = 12 × 6 = 72