SOLUTION: i buy 20 pencils at a certain price and 30 other more expensive pencils.the pencils cost me 90p.had i bought 30 of the cheaper pencils and the 20 of the dearer , i should have save

Question 616419: i buy 20 pencils at a certain price and 30 other more expensive pencils.the pencils cost me 90p.had i bought 30 of the cheaper pencils and the 20 of the dearer , i should have saved 5p.find the cost of of one of the dearer pencils.
Answer by josmiceli(19441) (Show Source): You can put this solution on YOUR website!
Let = price of one of the cheaper pencils
Let = price of one of the dearer pencils
given:

(1)
and

(2)
Multiply both sides of (1) by
and subtract (2) from (1)
(1)
(2)

and, since
(1)
(1)
(1)
(1)
(1)
1.5p is the price of one of the cheaper pencils
2p is the price of one of the dearer pencils
check:
(2)
(2)
(2)
(2)
You can check (1)
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