Answer:
<em>t = 1.51</em>
Step-by-step explanation:
<u>Exponential Model</u>
The exponential model is often used to simulate the behavior of a magnitude that either grow or decay in proportion to the existing amount of that magnitude.
The model can be expressed as

In this case, Mo is the initial mass of the radioactive substance and k is a constant which value is positive if the mass is growing or negative if the mass is decaying.
The value of k is not precisely given in the question, we are assuming 
The model is now

We are required to compute the time it takes the mass to reach one-half of its initial value:

Simplifying

Taking logarithms

Solving for t

The answer is $10 because 123=$6 and 4 hours is =$4 6+4=10
Answer:
Sophie has 12.5 cards
Step-by-step explanation:
Let
x -----> number of cards Sophie has
y -----> number of cards Jackie has
we know that
x+y=30 -----> equation A
y=x+5 -----> equation B
Solve by substitution
Substitute equation B in equation A and solve for x
x+(x+5)=30
2x=30-5
x=12.5 cards
Note I assume the problem was invented without taking into account the result, because the amount of cards should be a whole number
Answer:
18ywjhtzk8ywbhuj
Step-by-step explanation:
ujzjtzjdjwjduxhxhwbsusuww