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| Question 1040589:  A watch is sold at a profit of 20% on the cost price after allowing a discount of 20% on the marked price. Find the M.P of the watch is a profit of Rs. 100 is made on it.
 Answer by Theo(13342)
      (Show Source): 
You can put this solution on YOUR website! let p = profit let c = cost
 let s = selling price
 let m = markup price.
 
 selling price is equal to 20% off of the markup price.
 this means that s = m - .20 * m which becomes s = m * (1-.2) which becomes s = m*.80 which becomes s = .80 * m
 
 so far you have s = .80 * m
 
 you are given that p = 100.
 
 so far you have:
 
 p = 100
 s = .80 * m
 
 you are given that profit = 20% of cost.
 this means that p = .20 * c
 since p = 100, this means that 100 = .20 * c
 divide both sides of this equation by .20 and solve for c to get c = 500.
 
 so far you have:
 
 p = 100
 s = .80 * m
 c = 500
 
 since selling price is equal to cost plus profit, you get s = 500 + 100 = 600.
 
 in the equation of s = .80 * m, replace s with 600 to get 600 = .80 * m.
 divide both sides of this equation by .80 and solve for m to get m = 600 / .8 = 750
 
 your markup price is 750.
 you take 20% off of this to get a selling price of 600.
 your profit is 100 which means your cost has to be 500.
 a profit of 100 is equal to 20% of 500.
 
 all requirements of the problem have been satisfied.
 
 your solution is that the markup price is 750.
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