Answer: 
Step-by-step explanation:
You need to use the following formula:

Given the points A(6,3) and B(8,1), you can identify that:

Now, you can substitute these values into the formula
.
Therefore, you get this result:


Expand the equation.
Multiply (distribute) the first numbers of each set, outer numbers of each set, inner numbers of each set, and the last numbers of each set.
Combine like terms.
Solve the equation and simplify, if needed.
Given the triangles ABC and PQR.
Angle A = Angle P
Angle B = Angle Q
Angle C = Angle R
Angle B = 3v+4
Angle Q = 8v-6
Let's find v
3v+4 = 8v-6
-5v = -10
v = 2
Angle B = 3v + 4
Angle B = 3(2) + 4
Angle B = 10.
The correct answer is letter C. 10