Question

(2) An international call to a certain country costs Rs. 7

for the first minute, and Rs. 4 per minute thereafter.
Write down an expression in rupees for the cost of
a 10 minutes long international call. Simplify your
expression​

Answer 1

`y = 43`

Explanation:

Given

`First\ Minute = 7`

`Additional\ Minutes = 4` per minute

Required

Determine the cost of a 10 minutes call

First, we need to determine the expression for the call charges.

Let:

• x = minutes

• y = charges

The relationship between x and y is:

`y = First\ Minute + Additional\ Minutes(Number\ of\ minutes\ - 1)`

i.e.

`y = 7 + 4(x - 1)`

1 is subtracted from the total minutes because the first minute has a fixed rate.

For a 10 minutes call

`x = 10`

`y = 7 + 4(x - 1)`

`y = 7 + 4(10 - 1)`

`y = 7 + 4*9`

`y = 7 + 36`

`y = 43`

Hence, the charges for a 10 minutes call is: Rs.43