Question

the cost of 35 two different pens is rs 60.if the cost of cheaper pen is 1.50 and that of costlier pen is rs 2 then how many costlier pens are bought

Answer 1

$Total \: pens = 35$

$Let \: number \: \pink{cheaper }\:pens = x$

$and \: number \: \blue {Costlier } \:pens = (35-x)$

$Cost \: of \: each \: \pink{cheaper }\:pen = Rs\:1.50$

$Cost \: of \: each \: \blue{Costlier }\:pen = Rs\:2$

/* According to the problem given */

$Total \:Cost \: of \:Two \: type \:pens = Rs \:60$

$\implies 1.50x + 2(35-x) = 60$

$\implies 1.50x + 70 - 2x = 60$

$\implies - 0.5x = 60 - 70$

$\implies - 0.5x = - 10$

$\implies x = \frac{-10}{-0.5}$

$\implies x = 20$

$\therefore number \: \blue {Costlier } \:pens \\= (35-x)\\= 35 - 20 \\ \green {=15}$

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