A security system uses a 3-letter password, but no letter can be used more than once. How many possible passwords are there if 6 of the letters of the alphabet can be used by the system?

The correct answer is  × .

Step-by-step explanation:

Total number of alphabets the system can use = 6

In English language there are 26 alphabets and we are to use any 6 of them. Thus this can be done in ways.

A password is to be made for a security system using the above 6 letters and no letter can be used more than once.

Thus number of possible ways of making passwords of three letters using the above six letters are .

Total number of possible ways to choose 6 alphabets and make a password of 3 letters are  × .

i dont know it

step-by-step explanation:

c.

step-by-step explanation:

she should of added 9^2 and 12^2. that is because it is a^2+b^2=c^2. c^2 is the hypotenuse and should always be bigger than the other two numbers. which is why she should of added 9 squared and 12 squared together instead of 15 squared.