-a+(-b) where a= 6.05 and b= 3.611

-9.661

Step-by-step explanation:

In the given equation, a and b are negative. The values of a and b are given. If you insert the values into the given formula, the values become negative because of "-" in front of the a and b values.

-a + (-b)   =   -6.05 + (-3.611)

Because the second value is negative, the plus sign references to adding BOTH negative values together so it is just the same as saying:

-6.05 - 3.611

This gives you -9.661

Hope this helps!

e^-kt = n/n0 = 0.79  

-kt = ln 0.79  

t = - ln 0.79/0.0001  

= 2357 years

step-by-step explanation:

the answer is b.

64

step-by-step explanation:

c=2πr=2·π·8≈64