You decide to enroll in a plan that gives you a 10% discount if you make telephone calls 7pm – 6am. the per minute charge is $0.10 and the sales tax is 6%. on the first month’s bill you used the phone for 130 minutes 6am – 7pm and then 400 minutes 7pm – 6am. how much was your total bill?

If you used the phone 130 minutes from 6 am to 7 pm, that would cost $13.00. 400 minutes from 7 pm to 6 am at a 10% discount would cost you $36.00. Add totals to get $49.00. Tax at 6% is 2.94. Your total bill would be $51.94.

Total bill = (0.10+0.06) x 130 + (0.10+0.06) x 400 x 0.90
              = $ 51.94