Normal telephone charge = $25 per month --- (1)
Now if the guy uses regular charge calls to country A he will get 40% discount. The question asks us to find what is the maximum amount the guy can save if he uses the normal telephone charge rather than using regular charge calls.

So, inorder to get the maximum savings we need to find the maximum value of the regular charge calls. The higher the regular charge calls the maximum will be the savings.

The regular charge calls will be maximum only if the guy uses the max value of $1.6 often, i.e. if he speaks only 1 minute and covers the 1hr call duration in a certain month he will be charged $1.6 * 60min = $96

40% discount of 96 = $38.4 -- (2) for 1 month.

So he can save 38.4 - 25 = $13.4= C in a certain month by using the normal telephone charge.

- Deepak

DeepakR wrote:Normal telephone charge = $25 per month --- (1)
Now if the guy uses regular charge calls to country A he will get 40% discount. The question asks us to find what is the maximum amount the guy can save if he uses the normal telephone charge rather than using regular charge calls.

So, inorder to get the maximum savings we need to find the maximum value of the regular charge calls. The higher the regular charge calls the maximum will be the savings.

The regular charge calls will be maximum only if the guy uses the max value of $1.6 often, i.e. if he speaks only 1 minute and covers the 1hr call duration in a certain month he will be charged $1.6 * 60min = $96

40% discount of 96 = $38.4 -- (2) for 1 month.

So he can save 38.4 - 25 = $13.4= C in a certain month by using the normal telephone charge.

- Deepak

what if a person pays 25 dollars and get 40% discount and then uses it in the cheaper way such that he makes a single call of 60 mins, then in this case if you take max. call charges to be 96(1.6*60) and the min. call charges to be .6 * (3*1.6 + .8 * 57) +25 = 55.24 , then the saved money is more.....
please explain if i am missing something.