How can I work out the charge per unit of electricity in this Question

Question

The Question state.The charge for electricity consumption, E is partly constant and partly varies as the number,N of units used.The charge for 163 units is #453.80 while the charge for 42 units is #139.20.
Calculate the charge per unit of electricity.

Answer 1

To calculate the charge per unit of electricity, you need to determine the constant charge and the variable charge.

Let's assume the constant charge is "C" and the charge per unit of electricity is "x".

From the given information, we can set up two equations:

1) C + 163x = 453.80
2) C + 42x = 139.20

Now, we can solve these equations to find the values of C and x.

Subtracting equation 2 from equation 1, we get:

(163x - 42x) = (453.80 - 139.20)
121x = 314.60

Divide both sides of the equation by 121:

x = 314.60 / 121

x ≈ 2.60

Now, substitute the value of x into either of the original equations to solve for C:

C + 163(2.60) = 453.80
C + 424.80 = 453.80
C = 453.80 - 424.80
C = 29.00

Therefore, the constant charge (C) is 29.00 and the charge per unit of electricity (x) is approximately 2.60.

Hence, the charge per unit of electricity is #2.60.