Atyrannosaurus rex weighed about 1.4 tons more than one tenth the weight of a patagotitan mayorum. about how much did the tyrannosaurus rex weigh? a patagonian mayorum was a tyrannosaur that weighed about 76 tons

This is a very easy question here.

You have two dinosaurs. Let's just label them as Dinasour A (the Tyrannosaurus Rex), and Dinosaur B (the Patagonian Mayorum)

Dinasoar A weighs in at 1.4 tons more than a TENTH of Dinasoar B's weight
We know that Dinosaur B weighs in at 76 tons.

A tenth means exactly what it sounds like, 10/100. If it helps, you can think of it in terms of money, where a single Dime is a TENTH of a Dollar, because it takes 10 total Dimes to make $1

So, to fine a tenth of anything, you have to divide it by 10! 
76/10=7.6

7.6 is the tenth of the weight of Dino B. However, the question states that dino A weighs in at 1.4 tons MORE than a tenth, meaning addition.

So, 7.6+1.4=9

Dinosaur A, AKA the Tyrannosaurus Rex, weighs in at 9 Tons.

~Hope this helps!