Question 1116727
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1.  2 pencils and 2 rulers cost 56p  ====>   1 pencil and 1 ruler cost 28p.


2.  Now you have

    3 pencil and 1 ruler cost 50p   (first part of the condition),     and

    1 pencil and 1 ruler cost 28p.                  =====================>



    It implies that 2 pencils cost 50-28 = 22p.

    It means that 1 pencil cost 11p.
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Solved (mentally).