28 each book 155-15=140 and then 140÷5=28
18 that question is confusing so I guessed sorry dude
Answer:
The correct answer is:
Between 600 and 700 years (B)
Step-by-step explanation:
At a constant decay rate, the half-life of a radioactive substance is the time taken for the substance to decay to half of its original mass. The formula for radioactive exponential decay is given by:
First, let us calculate the decay constant (k)
Next, let us calculate the half-life as follows:
Therefore the half-life is between 600 and 700 years
Answer:
4
Step-by-step explanation:
The y-variable can be eliminated by adding 3 times the first equation to the second:
3(2x -y) +(x +3y) = 3(11) +(-5)
7x = 28 . . . . simplify
x = 4 . . . . . . . divide by 7
_____
Using Cramer's Rule, you can also find the x-value. The math is not so different.
x = ((-1)(-5) -(3)(11))/(-1(1) -3(2)) = -28/-7 = 4
Answer:
5 * 10 * 10 * 9 = 4500
Step-by-step explanation: