there are alternate interior angles when you have a line intersecting two parallel lines. This means..
A+D = G+K
E = F
A = C
B = D+F
your given D,G.B
from B = D+F
125 = 75+F
F = 50
which means F = 50
because a straight line is 180
E+G+K = 180
50+60+K=180
110+K=180
K = 180 -110
K = 70