Math, asked by poojapoorhapaashDu, 1 year ago

5 books and 7 pens together cost rs.79 where as 7 books and 5 pens together cost rs.77.Find the cost of 1 book and 2 pens.

mukesh3: pls tell me how to solve this question

Answers

Answered by DakshP

Let book cost= x Rs
Let pen cost= y Rs

ATQ
5x+7y=79 (i)
7x+5y=77 (ii)

Multiplying (i)(ii) by 7 and 5
35x+49y=553
35x+25y=385
- - -
Subtracting
24y=168
y=168/24
y=7

5x+7(7)=79
5x=79-49
5x=30
x=6

x+2y
6+2(7)
20 Rs

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