GEOMETRY PROOFS. NEED ANSWERS TO 15, 16, and 18!!!! BRAINLIEST ANSWER AND LOTS OF POINTS WILL BE GIVEN! please help i literally have no idea what i’m doing

GEOMETRY PROOFS NEED ANSWERS TO 15 16 and 18 BRAINLIEST ANSWER AND LOTS OF POINTS WILL BE GIVEN please help i literally have no idea what im doing class=