Question

The electricity bill of a certain establishment is partly fixed and partly varies as the number of units of electricity consumed. when in a certain month 540 units are consumed, the bill is rs1800. in another month, 620 units are consumed and the bill is rs2040. in yet another month 500 units are consumed the bill for that month would be?

Answer 1

The answer can be found out by HCF.

Thus, HCF of 540,620 and 500 is 40

Therfore, fixed unit = 40

The price of variable unit = x and fixed unit = y

Let us consider,

500x+40y=1800 --------->(1)

580x+40y=2040 --------->(2)

On solving the equations 1 and 2,

we come to a conclusion that x=3 and y=30/4

in 500 unit 40 fix and 460 varies

40*(30/4)+460*3=1680.

This is the corect answer.

Answer 2

Answer:

1680

We just need to check the difference on both the sides. No need to make any equations.