Count them
Three
Find the use's manual for the motherboard and you will find all required information.
9+1
You can use USB adapters. But USB does not cover as many interfaces as expension slots.
There are no guidelines on the number of expansion slots a system can have. Depending on case style, the number can vary between zero and eight.
You can upgrade Alienware desktops because of its many expansion slots.
There is no need to predict it, the reason is that is was designed and built that way. Designing in such slots allows for future upgrades and different utilisations of the computer.
No easy answer here; the type and model of the motherboard controls the number of slots for the cards.
This depends on the exact computer and motherboard. Some have none while some have as many as 8. These days, they tend to have 3-6.
Many desktop computers have expansion slots for sound and graphic cards. These are fairly standardized, however the number of available slots will be different for each machine. If you look at the back of your computer and see a series of long metal plates, count those, those are the number of free slots you have to use.
Motherboards can have one to six expansion card slots and a large number of USB connectors for adapters.
First find the total number by multiplying 13 racks by 18 slots for bikes. That will give you 234 possible slots for 234 bikes. Since there are already 93 bikes in slots already, subtract that number from 234 to get 141 slots left.