The cost of one book is x rupee and the cost of one pen is y rupee .Th

1.	The cost of one book is x rupee and the cost of one pen is y rupee .The total cost of 8 books and 4 pens is 140. The cost 4 books and 8 pens is 100. Cost of 1 pen is *
Answer» Answer: LET cost of book be x & cost of pen be y ⇒8x+5y=420;⇒5x+8y=321 Adding = 13x+13y=741;x+y=57 ____ (1) Subtracting = 3x−3y=99;x−y=33 substituting x=y+33 in EQUATION (1) we GET : y+33+y=57⇒2y=24⇒y=12 so x=12+33=45 cost of 1 book & 2 pens = 45+2(12)= 45+24 =69Rs

The cost of one book is x rupee and the cost of one pen is y rupee .The total cost of 8 books and 4 pens is 140. The cost 4 books and 8 pens is 100. Cost of 1 pen is *

Answer»

Answer:

LET cost of book be x & cost of pen be y

⇒8x+5y=420;⇒5x+8y=321

Adding = 13x+13y=741;x+y=57 ____ (1)

Subtracting = 3x−3y=99;x−y=33

substituting x=y+33 in EQUATION (1) we GET :

y+33+y=57⇒2y=24⇒y=12

so x=12+33=45

cost of 1 book & 2 pens = 45+2(12)= 45+24

=69Rs