Question

the price of 3pen and 7 pencils is 29 rs and the price of 4 pen and5 pencils is 30 rs what is the price of a pen and the price of a pencil​

Answer 1

Answer:

let the cost of the pen be X

Let the cost of pencil be y

according to the statement -

3x+7y =29 .... (1)

4x+ 5y = 30 ...(2)

By multiplying the equation (1) by 4 and equation (2) by 3 ,we get

4(3x+7y)=4×29

12x + 28y= 116 ..... (3)

3(4x+5y) =30×3

12x+15y=90....(4)

By subtracting equation (3)and (4) ,we obtain

12x+28y=116

-12x-15y=-90

13y = 26

y = 26÷13

y=2

By substituting Value of y in equation (4) we get

12x+15×2=90

12x+30=90

12x=90-30

12x=60

X=60÷12

X= 5

Therefore ,

the cost of one pen is rs2 and the cost of one pencil is rs 5