Answer:
20 units
Step-by-step explanation:
Initial particle concentration = 80 units
Particles removed each hour = 50% of the remaining particles
To find:
Particle concentration after 2 hours = ?
Solution:
Particles removed in 1 hour = 50% of remaining particles
i.e. Particles removed in 1 hour = 50% of initial concentration
Particles removed in 1 hour = 50% of 80 = 40
Particles removed in next 1 hour = 50% of remaining particles
i.e. Particles removed in next 1 hour = 50% of concentration after 1 hour
Particles removed in next 1 hour = 50% of 40 = 20
Total particles concentration removed in 2 hours = 40 + 20 = 60 units
Therefore, particle concentration after 2 hours = Initial concentration - Total particle concentration removed in 2 hours
= 80 - 60 = <em>20 units</em>
20x + 5y = 1900
x + y = 155....multiply by -20
----------------
20x + 5y = 1900
-20x - 20y = - 3100 (result of multiplying by -20)
--------------add
-15y = -1200
y = -1200/-15
y = 80 <== 80 per hr for the mechanic that worked 5 hrs
x + y = 155
x + 80 = 155
x = 155 - 80
x = 75 <== 75 per hr for the mechanic that worked 20 hrs
Answer: 26894
Step-by-step explanation:
Answer:
D
Step-by-step explanation:
hello :
The last two digits of the number are divisible by 4
exemple :
5028 is divisible by 4 because that 28 is divisible by 4.
538 is not divisible by 4 because 38 is not divisible by 4.
First, divide each amount by the downloads.
6.25/5 = 1.25 for each download
17.40/12 = 1.45 for each download
The online music store that offers 5 downloads for 6.25 is the better deal by 0.20 cents.
hope this helps