He was thinking of 23
I’ve attached my work on how I got it....
You do the opposite sign of what is given
Hope it helps!!
x = # of hours the bike was rented.
$40 = $12 + $7x
Subtract $12 from both sides.
$28 = $7x
Divide both sides by $7
4 = x
Sandy rented the bike for 4 hours.
Answer: 8.01
Step-by-step explanation:
Speed = distance/time = 280/4.5 = 62.44mph
Time = distance/speed = 500/62.44 = 8.0071 hrs
This is a fairly easy half-life problem
Each half-life reduces the radioactive material by one half.
So after 72 hours the radioactive material would have undergone 6 half-lives.
2^6 = 64.
So, there will be one sixty-fourth of the material left.
520 / 64 = 8.125 grams will remain.
radioactive decay is an exponential decay function.
Source:
http://www.1728.org/halflife.htm