Question

The total cost of 6 books and 7 pens is 79 rupees and the total cost of 7 book and 5 pens is 77 ruppes find the cost of 1 book and 2 pens (5 marks question)

Answer 1

let the cost of book be x and cost of pen is y

6x+7y=79....eq.1
7x+5y=77....eq.2
(multiply eq.1 with 5 and eq.2 with 7)

we get,
30x+35y=395
49x+35y=539
change the signs of eq.2
(subtract both the eq.s)
we get,
-19x=-144
x=144/19
putting x =144/19 in eq.2
we get,
7*144/19+5y=77
1008/19+5y=77
5y=77-1008/19
5y=455/19
y=455/19*5
y=91/19



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