Question

Four pens and five erasers cost 32 .five pens and four erasers cost 31 find the cost of each pen

Answer 1

Step-by-step explanation:

4X+5Y=32 ----------|1|

5X+4Y=31--------------|2|

MULTIPLYING |1| BY 4 AND |2| BY 5

16X + 20Y = 128

25X+20Y= 155

SUBTRATING |1| AND |2|

25X+20Y =155

- 16X+20Y =128

________________

9X=27

9X=27

x=27/9

x= 3

Hope it helps

Answer 2

Given - Cost of combined pens and erasers

Find - Cost of each pen

Solution - The cost of each pen is Rupees 3

Let the cost of one pen be x and the cost of one eraser be y. Now, as per the first statement, we get the mathematical expression -

4x + 5y = 32 (Equation 1)

The mathematical expression following the second statement -

5x + 4y = 31 (Equation 2)

Multiplying equation 1 with 4 and equation 2 with 5. The new mathematical expression we get is as follows -

16x + 20y = 128 - Equation 3

25x + 20y = 155 - Equation 4

Subtracting Equation 3 from equation 4

25x + 20y = 155

-16x - 20y = -128

On subtraction we get -

9x = 27

x =27/9

= 3

Therefore the cost of each pen is Rupees 3.