The easiest place to start for this is to calculate how much it costs per minute of call time. To do this, if we know that it costs 52.5 cents to call for 3.5 minutes, we can divide those two numbers to get how much it costs per minute.
52.5/3.5 = 15
If it costs 15 cents per minute, and we want to know how much it would cost to call for 5.33 (5 and 1/3 of a minute), then we multiply our 15 cents a minute by the number of minutes to get the final cost.
15 x 5.33 = 79.99
Because we can't have 99/100 cents, rounding up to 80 is important to get a proper answer.
