That's an error. A telent is a unit of weight, like a pound. The exact weight varied by region, but Wiki says that an Egyptian talent was 60lb.
In order to know how much money we are talking about, you would need to know whether it was a talent of bronze or silver or gold. Later in the article it suggests that it was Bronze, and says that the 15 talent "surcharge" was just a way of converting from silver to bronze.
If you want to guess how much it would be worth today, 75 talents x 60 lb = 4,500 pounds x 14.58 troy ounces per pound = 65,600 troy ounces of silver x $17 per ounce = $1.1 million.
However, if they paid in bronze, which today is a lot cheaper than silver, it would be 90 talents x 60lb x $2 per pound = $10,800
Thanks, you beat me to it.
A talent was the load a man could carry.
Its value is remarkably difficult to equate to today, because the relative scarcity of metals would mean that the purchasing power of metals might be very different then and now.