After receiving two successive raises Harsh's salary became 15/8 times of his initial salary.By how much percent was the salary raised the first time if the second raise was twice as much as high(in percent) as the first?

• Let Initial salary was Rs. 100.
  After two rais it become 15/8 i.e. (15*100)/8 = Rs. 187.5
  Raise = 187.5 -100 = 87.5
  Using formula,
  [(first raise + 2nd rais) + (first raise *2nd raise)/100] = 87.5
  X +2X + (2X^2)/100 = 87.53
  
  300X + 2X^2 = 8750
  
  X^2 + 150X = 4375
  
  X^2 + 150X - 4375 = 0
  X^2 + 175 X - 25X - 4375 =0
  
  X = -175, 25 (Negative value is not possible)
  
  So, X = 25%
  Second Raise was 2X = 2*25 = 50%
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