Question 1193508
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Armando is selling rulers. he bought rulers for 0.20c each, and sold them (except foe broken ones) 
at N$1.10 each to make a profit of N$306.50. The number of broken rulers is 38. How many rulers did he buy?
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Let n be the number of rules he bought.

Then the number of rules he sold was (n-38).



He spent 0.2*n  dollars to buy n rules.

He collected 1.10*(n-38) dollars by selling the rules.



His profit is the difference

    1.10(n-38) - 0.2n   dollars.



The profit equation is

    1.10(n-38) - 0.2n = 306.50   dollars.



Simplify and find n

    1.10n - 1.1*38 - 0.2n = 306.50

            0.9n          = 306.50 + 1.1*38

            0.9n          =      348.3

               n          =      348.3/0.9 = 387.


<U>ANSWER</U>.  Armando bought 387 rulers.
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Solved.