If a discount of 20% off the retail price of a desk saves mark$45 how much did he pay for the desk?

$180

Step-by-step explanation:

what is 45 20% of? This is what we need to find! To do this we have to take 45 and divide it by .2 which will give us 225. To check that this is the answer we take 45 and divide it by 225. This brings us back to 20%. He wouldve paid $225 for the desk, but there was a $45 discount, and after subtracting the discount we are left with $180

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.