# 5 pencils &7 pens together cost Rs.50 whereas 7 pencils & 5 pens together costs Rs. 46.find the cost of one pen & one pencil

2

• Brainly User
2014-05-29T13:07:29+05:30

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Let pencil be x and let pen be y
5x+7y=50
7x+5y=46
multiply first equation by 7
35x+49y = 350
multiply second equation by 5
35x+25y=230
solving them we get 24y=120 which gives y is 5 rupees
substituting in second equation we get x is 3 rupees

• Brainly User
2014-05-29T19:42:33+05:30
5 pencils &7 pens together cost Rs.50 whereas 7 pencils & 5 pens together costs Rs. 46.find the cost of one pen & one pencil

Solution:
let cost(in RS) of one pencil = x
and cost (in RS) of one pen = y
Therefore , according to question
5x+7y = 50  ........ (1)
7x + 5y = 46  .........(2)
Multiply equation 1 by 7 and equation by 5 we get
7(5x+7y)= 7*50
35x +49y = 350 .......(3)
and
5(7x +5y) = 5*46
35x +25y = 230 ....... (4)

Subtract equation 4 from equation 3 , we get
35x + 49y - 35x - 25y = 350 -230
49y -25y = 120
24y = 120
y = 120 /24
y= 5
Substitute y=5 in equation 1 , we get

5x +  7*5 =50
5x+35 =50
5x = 50 - 35
5x =15
x= 15/5
x=3

Hence Cost of One Pencil = x =3
Cost  of One Pen =y =5

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