The cost for 1 cd would be $3.00. To figure this out divide 12 by 4.
The argument is valid by the law of detachment.
(3,24)(7,56)
slope = (56 - 24) / (7 - 3) = 32/4 = 8
y = mx + b
slope(m) = 8
(3,24)...x = 3 and y = 24
now we sub
24 = 8(3) + b
24 = 24 + b
24 - 24 = b
0 = b
so ur equation is : y = 8x + 0...or just y = 8x
to find ur answer, take ur answer choices and sub them into y = 8x and whichever one is true is ur answer.