Question

NCERT chapter 3 exercise 2
5 pencils and 7 pens together cost Rupees 50 where is 7 pencils and 5 pens together cost rupees 46 find the cost of one pencil and that of one pen please answer it's very fast

Answer 1

Let the cost of pencils be "x"
and cost of pens be "y"

ATQ,

5x+7y= 50------------(1)
and 7x+5y=46-------(2)

multiplying equation (1) with 7 and equation (2) with 5, we get
35x+49y=350
35x+25y= 230

equating both we have
y=5

then putting the value of y in eqn (1)
we have
5x+7*5=50
5x+35=50
5x=50-35
5x=15
therefore x= 3

hope it helps.. genius..

Answer 2

$\bf\huge\boxed{\boxed{\bf\huge\:Hello\:Mate}}}$

By the Information

Let pencil be p and let pen be y

5p  + 7y = 50  ........ (1)

7p + 5y = 46  .........(2)

Multiply 1 by 7 and equation by 5

7(5p + 7y) = 7 × 50

                       

35p + 49y = 350 .......(3)

                 

5(7p + 5y) = 5 × 46

                       

35p + 25y = 230 ....... (4)

Subtract  4 from equation 3

                           

35p + 49y - 35p - 25y = 350 -230

                           

49y - 25y = 120

                           

24y = 120

                               

$\bf\huge y = \frac{120}{24}$

                               

y = 5

Now put y = 5 in equation 1

               

5p +  7 × 5 = 50

               

5p + 35 = 50

               

5p = 50 - 35

               

5p = 15

               

$\bf\huge p = \frac{15}{5}$

               

p = 3

Cost of One Pencil = 3

Cost  of One Pen = 5

$\bf\huge\boxed{\boxed{\bf\huge\:Thanka}}}$