help with geometry

Well, m∠ABR is equal to 90° because the angle formed by a tangent and the radius or diameter has to be a right angle. Since we know that m∠ABR = 90° and m∠CBA = 25°, and m∠CBR = m∠ABR - m∠CBA, then m∠CBR = 90° - 25º = 65º.

 

Answer: m∠CBR = 65°