Question

5 pencil and 7 pen cost rs 195 while 7pencil and 5 pen cost rs 153 find the cost of 1 pen and 1 pencil

Answer 1

5 Pencils + 7 Pens = Rs 195 ------------ [ 1 ]

7 pencils + 5 pens = Rs 153 ------------ [ 2 ]

[ 1  } x 7 : 35 Pencils + 49 pens = Rs 1365 ------------ [ 1a ]

[ 2 ] x 5 : 35 pencils + 25 pens = Rs 765  ------------ [ 2a ]

Find the cost of 1 pen:

[ 1a ] - [ 2a ] :

24 pens = Rs 600

1 pen = 600 ÷ 24

1 pen = Rs 25

Find the cost of 1 pencil:

From [ 1 ] : 5 Pencils + 7 Pens = Rs 195

5 Pencils + 7(25) = Rs 195

5 Pencils = 195 - 175

5 Pencils = Rs 20

1 Pencil = 20 ÷ 5 = Rs 4

Find the cost of 1 pen and 1 pencil:

1 pen + 1 pencil = 25 + 4 = Rs 29

Answer: 1 pen and 1 pencil cost Rs 29

Answer 2

Hey friend here is your answer!!!

Let cost of pencil be x
and cost of pen be y

According to first line
5x + 7y = 195
According to second line
7x + 5y = 153

now in first equation
5x + 7y = 195
5x = 195 - 7y
x = 195 - 7y/5

now in second equation
7x + 5y = 153
putting the value of x
7( 195 - 7y/5) + 5y =153
1365 - 49y/5 + 5y/1 = 153
1365 - 49y + 25y/5 = 153
1365-49y +25y = 765
1365-24y = 765
1365=765+24y
600 = 24y
25 = y

so cost of 1 pen is Rs 25

now putting value of y in x equation
x = 195-7y/5
x = 195 - 7×25/5
x = 195 - 175/5
x = 20/5
x = 4

so the cost of 1 pencil is Rs 4


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