Question

(ii) 5 pencils and 7 pens together cost ` 50, whereas 7 pencils and 5 pens together

cost ` 46. Find the cost of one pencil and that of one

Answer 1

Let the cost of 1 pencil be x
Let the cost of 1 pen be y

A/Q

5x +7y=50 => 35x + 49y =350.....(i)
and
7x + 5y = 46 => 35x + 25y=230.....(ii)

Subtracting (ii) from (i) we get,
24y=120 => y=120/24=5

putting value of y in eq (i)
35x+245=350 => x=105/35=3

THEN COST OF ONE PENCIL IS ₹3 AND COST OF ONE PEN IS ₹5

HOPE THIS HELPS BRO : D

Answer 2

5 pencils + 7 pens = Rs 50 ------------------ [ 1 ]

7 pencils + 5 pens = Rs 46------------------ [ 2 ]

Make the number of pencils the same:

[ 1 ] x  7 : 35 pencils + 49 pens = Rs 350------------------ [ 3 ]

[ 2 ] x 5 : 35 pencils + 25 pens = Rs 230------------------ [ 4 ]

[ 3 ] - [ 4 ]

24 pens = Rs 120

1 pen = 120 ÷ 24

1 pen = Rs 5

Find the cost of 1 pencil:

Sub 1 pen = Rs 5 into equation [ 1 ]:

5 pencils + 7 pens = Rs 50

5 pencils + 7 (5)  = 50

5 pencils + 35 = 50

5 pencils = 15

1 pencil = 15 ÷ 5

1 pencil =  Rs 3

Answer: 1 pencil = Rs 3 and 1 pen = Rs 5