hi afo99,As you know that HSRP uses this virtual MAC address, 0000.0C07.ACxy, where xy is the HSRP group number in hexadecimal.so your HSRP group no is 37 which is in a decimal format so we need to change it into hexadecimal37 = 0010 0101 binary0010 ...

thank you sir your explanation help me :)