take a look at the order of the letters of ur triangles.
ABC and PQR.....it says they are congruent....so they r equal.
And the order of the letters means : < A = < P, and < B = < Q, and < C = < R.
so if < B = < Q....set them equal to each other and solve for v
3v + 4 = 8v - 6
6 + 4 = 8v - 3v
10 = 5v
10/5 = v
2 = v
now we sub our 2 in for v
< B = 3v + 4......3(2) + 4 = 10
< Q = 8v - 6.......8(2) - 6 = 10
so < B and < Q both equal 10 <==