Since these triangles are similar....angle BCA = angle EFD
And ED = EF....so angle EDF = angle EFD
So
Angle DEF + Angle EDF + Angle EFD = 180
42 + Angle EFD + Angle EFD = 180
2 *Angle EFD = 180 - 42
2 * Angle EFD = 138 divide both sides by 2
Angle EFD = 69° = Angle BCA