Solve the equation:
5 3
x – —— = – ——
7 7
5
Add —— to both sides, so you get x isolated at the left-hand side:
7
5 5 3 5
x – —— + —— = – —— + ——
7 7 7 7
3 5
x = – —— + ——
7 7
Now, add those fractions at the right-hand side of the equation:
– 3 + 5
x = —————
7
2
x = —— <——— this is the answer (first option: 2/7).
7
I hope this helps. =)
For this case we have an equation of the form:
y = A * (b) ^ t
Where,
A: initial amount
b: decrease rate
t: time in years.
Substituting values we have:
7 = A * (0.5) ^ ((1/20) * t)
For t = 45 years we have:
7 = A * (0.5) ^ ((1/20) * 45)
Clearing A:
A = 7 / ((0.5) ^ ((1/20) * 45))
A = 33.3
Answer:
the density of the substance when it was deposited 45 years ago was:
A = 33.3 milligrams per square centimeter
Answer:
y=10
Step-by-step explanation:
10^2-100=0
100-100=0
0=0
