The current yield is calculated by coupon/bond price. But I always stuck at some steps. Could someone help me?

Let B, be the value at time t in years of a bond with maturity T paying annual coupon c with face value 1 and yield to maturity y compounded annually. Thus 1 1 B. + yL T- (1+y) (1 + y) Show that the fractional increases in value per year of the bond is AB B1+1-B, y - current yield B B = 1