Question

The cost of five pens and eight pencils is 120/- while the cost of eight pend and five pencils is 153. What is the cost one pen and one pencil ??

Answer 1

Answer:

The cost of one pen is 16/-

The cost of one pencil is 5-

Step-by-step explanation:

Given,

The cost of five pens and eight pencils is 120/-

The cost of eight pens and five pencils is 153/-

Let,

The cost of each pen be x

The cost of each pencil be y

Then,

According to the first statement,

5 pens and 8 pencils cost 120/-

5x+8y=120-------EQUATION  1

According to the second statement,

8 pens and 5 pencils cost 153/-

8x+5y=153--------EQUATION 2

Now, solve equation 1 and 2

5x+8y=120

8x+5y=153

For solving the equations, either x term's or y term's coefficients should be equal..

We'll solve for x coefficient..

For x's coefficient to be same, the first equation should be multiplied with 8 and the second equation should be multiplied with 5

The final equation will be

40x+64y=960

40x+25y=765

______________

      39y=195

         y=195/39

         y = 5

Substitute the value of y in equation 1

5x+8y=120

5x+8(5)=120

5x+40=120

5x=120-40

5x=80

x=80/5

x = 16

So,

THE COST OF ONE PEN IS 16/-

THE COST OF ONE PENCIL IS 5/-

Answer 2

Answer:

le

Step-by-step explanation:

let the cost of 1pen and pencils

5x+8y=120(1)

8x+5y=153(2)

adding both sides

13x+13y=273

x+y=21 (3)

subtraction (1) and(2)

3x+3y=33

x-y=11 (4)

now add (3),(4)

2x-32

x=16

substituting x=16

16+y=21

y=5

hence cost of 1pen and pencils is rs=16 and rs=5