Answer
A single fixed amount cannot be quoted for long: the base taxi fare in Montevideo is revised periodically. A previous estimate of around 70 pesos may no longer reflect the current price. Check the official city fare schedule for the current starting fare and the cost of subsequent increments.
The starting fare is only the beginning of the calculation. The taximeter takes into account distance traveled and time, so traffic jams, waiting, and a longer route will increase the total. Different rates may apply at certain times, on certain days, or for certain services, so check before traveling.
When getting into the taxi, make sure the meter starts at the correct initial fare. If you need a predictable budget, compare ride-hailing services, but read the terms governing changes to the estimated price. For airport trips, also ask about any additional fees and baggage arrangements.