Given IP  72 . 84 . 250 . 136 / 13  
#1. & 2.  Find the SubNetwork 

#3.  Find the First useable IP address  72 . 80 . 0 . 1 
#4.  Find the Broadcast address  72 . 87 . 255 . 255 
#5  Find the Last useable IP address  72 . 87 . 255 . 254 
#6.  What is the Total Number of IPs per Subnet?  524288 
#7.  How many useable Hosts address per subnet?  524286 
#8.  What is the Next Subnet Number?  72 . 88 . 0 . 0 
#9.  What IP Class is this?  Class A 
#10.  How many possible Subnetworks with this class?  Bits this Class = 8 Bits Subnet Mask= 13 2^ 5 = 32 