Question
If the total cost of 7 books and 5 pens is Rs. 350 and the
total cost of 3 books and 2 pens is Rs. 160, then find the cost of 10 books.Solution
ATQ,
Let the cost of one book and one pen be Rs. x and Rs. y, respectively.
ATQ;
7x+5y=350........(I)
3x+2y=160.......(II)
Multiply Equation (II) by 5 and Equation (I) by 2, then subtract:
(3x+2y)×5−(7x+5y)×2
15x+10y−14x−10y=800−700
x=100
Cost of 10 books = 10×100=1000 Rs.
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