Problem on Chapter Sets

Question

In a battle 70% of the combatants lost one eye, 80% an ear, 75% an arm, 85% a leg, x% lost all the four limbs. What is the minimum value of x ?

Answer 1

let there be 100 combatants, of which 
 30 did not lost an eye; therefore, 70 did lost one, of which 
 20 did not lost an ear; therefore, 50 did lost one, of which 
 25 did not lost an arm; therefore, 25 did lost one, of which 
 15 did not lost a leg; therefore, 10 did lost one 
Finally, these 10 are the most unlucky ones. 

therefore 
minimum = 10 %