Can someone please help me it’s for geometry thank you :)

Answer:
QST = 2x= 2*20 = 40°
Step-by-step explanation:
RSQ+QST= RST
we know that RST is 124
So,
84+2x= 124
Bringing 84 to the other side it becomes negative
2x= 124-84
= 40
Therefore,
x= 40/2
= 20 °
Here's your answer :)