4. Lucy is k years old. She has a sister who is three years younger than she is and another sister who is five years less than twice Lucy's age. Write an expression, in
simplified form, for the sum of the three girls' ages.

4k - 8

Step-by-step explanation:

Lucy is k years old so we know k is an important part of this problem.
Sister 1 is 3 years younger, so she is k - 3 years old.
Sister 2 is 5 years less than twice Lucy's age therefore, she is 2k (twice Lucy's age) - 5 years old.
Now we have: k + (k - 3) + (2k - 5)
We can simplify like terms with the k's and get 4k. then we add (-3) and (-5) to get 4k - 8.

Hope this helps!

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.