Question

The total cost of 8 books and 5 pens is 92 and the cost of 5 books and 8 pens is 77.Find the cost of 3 books and 2 pens ?

Answer 1

And x=9
Therefore, books=27 and pens=8

Answer 2

Question:-

The total cost of 8 books and 5 pens is 92 and the cost of 5 books and 8 pens is 77.Find the cost of 3 books and 2 pens ?

Solution:-

{ According to question }

• The total cost of 8 books and 5 pens is 92
• The cost of 5 books and 8 pens is 77

Let, x be the cost of one book & y be the cost of one pen.

Now, according to question & assumption

We from an equation

—› 8x + 5y = 92 ........ ( 1 )

—› 5x + 8y = 77 ........ ( 2 )

{To find value of y ( pen ) }

multiply eq. ( 1 ) by 5, we get,

—› 40x + 25y = 460 ....... ( 3 )

multiply eq. ( 2 ) by 8, we get,

—› 40x + 64y = 616 ....... ( 4 )

Now, subtract eq. ( 4 ) from eq. ( 3 )

40x + 25y = 460

- ( 40x + 64y = 616 )

____________________

-39y = - 156

39y = 156

y = 156/39

y = 4

{To find value of y ( pen ) }

Now, put value of y in eq. ( 1 )

—› 8x + 5(4)= 92

—› 8x + 20 = 92

—› 8x = 92 - 20

—› 8x = 72

—› x = 72/8

—› x = 9

from value of x & y we know cost of one book is {unit} 9 & cost of one pen is {unit} 4 respectively.

—› Cost of 3 books = 9 × 3

—› Cost of 3 books = {unit} 27

and

—› Cost of 2 pens = 4×2

—› Cost of 2 pens = {unit} 8

Hence the cost of 3 books is {unit}

27 and 2 pens is {unit} 8 .