Explanation:
( ) . . . . stuff that is given
∠ABE ≅∠DEG . . . . corresponding angles at a transversal
∠ABC +∠CBE = ∠ABE . . . . angle addition postulate
∠CBE = ∠ABE -∠ABC . . . . subtraction property of equality
∠DEF +∠FEG = ∠DEG . . . . angle addition postulate
∠FEG = ∠DEG -∠DEF . . . . subtraction property of equality
∠FEG = ∠ABE -∠ABC . . . . substitution property of equality
∠CBE = ∠FEG . . . . substitution property of equality
CB║EF . . . . converse of corresponding angles theorem
