Final answer:
The Tyrannosaurus rex weighed approximately 9 tons.
Step-by-step explanation:
To determine the weight of the Tyrannosaurus rex, we need to find one tenth the weight of Patagotitan mayorum, which is 76 tons. One tenth of 76 tons is 7.6 tons. We then add 1.4 tons to this, as the Tyrannosaurus rex weighs about 1.4 tons more than one tenth the weight of Patagotitan mayorum. Therefore, the weight of the Tyrannosaurus rex is approximately 9 tons.