Question

the total cost of 6 books and 7 pens is 79 rupees and the total cost of 7 books and 5 pens is 77 rupees. find the cost of 1 book and 2 pens​

Answer 1

Answer:

Let 1 book = x

1pen = y

According to question,

6 X + 7 y =79 -------(1)

7 x + 5 y= 77 --------(2)

equation 1 ×5 and equation 2 ×7

30 X + 35 y = 395 ---------(3)

49 X + 35 y = 539. ----------(4)

by elimination method

-9 x= -144

9 x = 144

x=144/9

x=16

Then put the value of x in equation (2)

7 × 16 + 5y = 77

112 + 5y = 77

5y = 77 - 112

5y = -35

y = -7

Therefore the cost of 1 book = x = 16 and the cost of 2 pens = 2y = 2 × (-7) = -14