The total expense of a boarding house is partly fixed and partly variable with the number of boarders. When the number of boarders is 25, then the charge is Rs 70 per head and the same is Rs 60 when the number of boarders is 50. What would be the charge per head if there are 100 boarders?
Select the correct option:  A) 51  B) 52  C) 53  D) 54  E) 55
consider x as partly fixed and y as partly variable.   as number of boarders has been changing consider it as y.   sum(total expense including fixed n change)=x+25y=1750(25*70)   x+60y=3000(60*50)   by solving those equations v get x as 500 and y as 50   now do for 100 boarders 100y=100*50=5500   per head consists of 5500/100= 
<gadget id="calculator">5500/100</gadget>
<output>55</output>
55.   ANSW55R:55
<result>E</result>
The total expense of a boarding house is partly fixed and partly variable with the number of boarders. When the number of boarders is 25, then the charge is Rs 70 per head and the same is Rs 60 when the number of boarders is 50. What would be the charge per head if there are 100 boarders?