Can someone please help me with this ruler problem? I have a hard time understanding on how to read a ruler. Please help immediately! :(

How many different three-digit numbers can be formed using the digits 1 comma 2 comma 9 comma 6 comma 4 comma 3 comma and 8 without repetition? for example, 664 is not allowed.

Acertain volume of water contains 100000 hydrogen atoms and 50,000 oxygen atoms how many hydrogen atoms are in a volume of water containing 4 million oxygen atoms

Fixed rate mortgage offer: purchase price: $170,000 down payment ($34k): 20% term: 30 years interest rate: 4.25% property tax (yearly): $1,500 homeowner’s insurance (yearly): $1,000 use this example from a fixed-rate mortgage calculator to you answer the questions. keep the page open after you complete this question. according to the calculator, the monthly payment demarco and tanya should anticipate paying for principal and interest is $208. $877. $669. $1,200.