The sum of three numbers is 1770 . If the ratio between the first and second be 5 : 7 and that of between the second and third be 2 : 5, then find the second number.

420

   I     :      II      :      III      :    Total

   5    :       7

                 2      :        5  

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

  10     :       14      :       35     :     59

59R = 1770

1R = 30 

14R = 14 × 30 = 420