Which expression is equivalent to 12 X to the 15th power over 3X to the 18th power

12X^-3

Step-by-step explanation:

12X^15 / 3X^12 = 0. The properties of exponents would say that we have to subtract the exponents in division, but we need the same bases first. In order to get the bases the same we need to divide both sides by 1/4. That will make 12 stay 12 and 3 become 12. Now we subtract the exponents using the properties of exponents with the same base. We end up left with 12x^-3.

I apologize if I made an error. I would be careful since I'm not to sure about my answer myself.

a) one student is chosen from classroom a, then a student is chosen from classroom b.  

step-by-step explanation:

independent events are ones in which the probability of one event does not affect the probability of the second event.

one student is chosen from classroom a; this does not affect the chances of choosing a student from classroom b.   this makes these independent events.

when one card is chosen from a standard deck and then set aside before a second card is chosen, the probability of the second card being chosen changes.   this makes them dependent events.

when one student is chosen from classroom a and then a second student is chosen from classroom a, the probability of choosing the second student changes.   this makes them dependent events.

when a letter is chosen from the alphabet and then a second letter is chosen, the probability of choosing the second letter changes.   this makes them dependent events.