You have an Azure subscription.

Box-1 : 3

Initial starts 2 VM's 15 minutes have passed. at 10 minutes 1 VM was added we now have 3 VM's. Cool down is 5 Minutes before another 10 minute wait cycle starts so the answer is 3.

Box-2: 1

Initial 5 VM's 60 minutes Pass. 1 VM removed every 15 minute cycle. 10 minutes wait timer plus 5 minute cool down equals 15 minutes cycle. Four 15 minute cycles pass equaling 60 minutes removing 4 VM's. We have 1 VM left.

Default Scale in and Out Default Durations are 10 minutes with 5 minute cool down.

The default scale set settings in Azure are:

-Minimum number of instances 1

-Maximum number of instances 10

-Scale out CPU threshold (%) 75

-Duration in minutes10

-Number of instances to increase by 1

-Scale in CPU threshold (%) 25

-Number of instances to decrease by -1

https://learn.microsoft.com/en-us/azure/virtual-machine-scale-sets/virtual-machine-scale-sets-autoscale-portal#create-a-rule-to-automatically-scale-in