Answer:
I think it is D I am sorry if wrong
a coin always has a 50% chance of landing on either heads or tails.
D = r t
384 = 640 * t
384/640 = t
.6 = t .6 of an hour
.6 hr * 60min/1 hr = 36 minutes (just in case it needs to be in minutes)
I'm guessing the 20 percent off is from the $36.81 so you take 36.81 times 0.80 making it $29.448. Take 90 dollars and minus that amount.
Answer: $60.552
Rounded Answer: $60.55 or $60.60 or $61
Not sure if this helped, but yeah.....
