AB = 14
m∠F = 39°
Well the explanation here is simple.
Since the given states that the two triangles, ΔABC and ΔDEF, are congruent, they must have congruent/corresponding parts.
So AB is the same as DE which measures 14, so therefore AB must measure 14.
The same explanation goes to m∠F, ∠C is congruent to ∠F so it must measure 39° too.
