Answer:
x = 3
Step-by-step explanation:
To solve this problem, we need to remember the exterior angle theorem. This theorem tells us that: "The exterior angle of a triangle is equal to the sum of the two opposite interior angles"
In the picture, we would have that the angle ∠QRT =∠RTS + ∠TSR
Substituting the values from the figure we get:

Thus, the value for x is 3