1) 3 books and 10 pens together cast Rs.300.2 books and 3 pens together cost Rs. 145. Find
the cost of l book and 3 pens.​

1 thought on “1) 3 books and 10 pens together cast Rs.300.2 books and 3 pens together cost Rs. 145. Find<br />the cost of l book and 3 pens.​”

1. Answer:

   Let the cost of 1 book =x

   And the cost of 1 pen =y

   ⇒5x+7y=79

   ⇒7x+5y=77

   Equation (1) × 7 : 35x+49y=79×7

   Equation (2) × 5 : 35x+25y=77×5

   Subtract two equations ;

   ⇒24y=168

   ⇒y=7

   ⇒x=6

   Total cost of 1 book and 2 pens =x+2y=6+14=20

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