Question

The cost of 7 litres milk and 9 litres of oil is a 820 rupees. The cost of 6 letters milk and 5 litres of oil used for 540 rupees. what is the cost of 1 litre milk?what is the cost of 1 litre of oil?​

Answer 1

Answer:

Let the cost of 1 litre milk be x and the cost of 1 litre oil be y.

According to 1st condition, 7x+9y=820......(1)

According to2nd condition, 6x+5y=540.....(2)

By Elimination method,

Multiply eq. 1st from 6 and eq.2nd from 7, we get

42x+54y=4720..........(3)

42x+35y=3720..........(4)

Subtract eq. 3rd from eq. 4, we get

42x+54y=4720

-42x+(-)35y=-3720

⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻⁻

0 +19y = 1000

y = 1000/19

Put the value of y in eq.2d, we get

42x+35×1000/19=3720

42x+35000/19=3720

42x=3720-35000/19

42x=33480-35000/19

42x= -1520/19= -80

x= -80/42

x= -40/21

y=52.6 and x=1.91

Hence, the cost of 1 Litre milk is 1.91 and the cost of 1 litre oil is 52.6.

Hope it is helpful for you.