With 3 questions and show all !

Question 1:
Since the triangles are congruent, we know that QS = TV
This means that 
3v + 2 = 7v - 6
Subtract both sides by 2
3v = 7v - 8
Subtract 7v from both sides
-4v = -8
Divide both sides by -4
v = 2
Plug this value back into 3v + 2 and you get 8.
QS = 8
Since the triangles are congruent
QS = 8    AND    TV = 8

Question 2:
So we know that AC = AC because that's a shared side.
It's also given that BC = CD.
In order for two triangles to be congruent by SAS, the angle between the two sides must be congruent.
That means angle C must be congruent to angle C from the other triangle.

Question 3:
We know that AC = AC because it's a shared side.
We also know that angle A from one triangle is equal to angle C from the other.
However, for a triangle to be congruent by SAS, the congruent angle must be between two congruent sides. 
In order for us to prove congruence by SAS, AD must be congruent to BC.

Have an awesome day! :)