Staples sells cds ($2.00) and boxes of computer paper ($3). if total sales were $1,560 and customers bought 5 times as many cds as boxes of computer paper, how many cds were sold?

Solution:

CDs: c, Boxes of computer paper: p

c = 5p

2c + 3p = 1560 (the total sales of the items equals $1560)

Plug in the variable value:

2(5p) + 3p = 1560

10p + 3p = 1560

13p = 1560

divide by 13:

p = 120

c = 5 * 120

c = 600

Verify:

2 * 600 + 3 * 120 = 1560

1200 + 360 = 1560

1560 = 1560

600 CDs were sold

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.

47 - 90 = 43

43 - 180 = x

x = 137