8hrs = 480mins
6hrs = 360 mins
472/480 = 0.983...
0.983... x 360 = 354
D) 354
Answer:
Probability is: 
Step-by-step explanation:
From a deck of 52 cards there are 26 black cards. (Spades and Clubs).
Also, there are 26 red cards. (Hearts and Diamonds).
First, we determine the probability of drawing a black card.
P(drawing a black card) =

Now, since we don't replace the drawn card, there are only 51 cards.
But the number of red cards is still 26,
∴ P(drawing a red card) =

Now, the probability of both black and red card =

Hence, the answer.
From 1st equation
d + e = 2
d = 2 - e
From 2nd equation, subtitute d with 2 - e
d - e = 4
2 - e - e = 4
2 - 2e = 4
-2e = 2
e = -1
Find d
d = 2 - e
d = 2 - (-1)
d = 3
The solution is (3,-1)