Answer:
Don't feel that way ok , every thing is going to be ok in the end an if it's not ok its the end. you can fight through it don't let anyone or anything get to you , just know that we all are here for you an, every one on this is unique in their own way ! just love your self an others will do the same love you all
The two different isotopes have weights :
w1 = 78.918 amu
w2 = 80.916 amu
average weight w3 = 79.903 amu
The mixing of two components can be modeled as
let the fraction of w1 be 'x'
hence 
now this is a linear equation in 'x'. Substituting the values we get
x = 0.507
hence the percentage of Br79 = 50.7% and the percentage of BR81 = 49.3%
Answer & Explanation:
Relative age is the age of a rock layer (or the fossils it contains) compared to other layers. It can be determined by looking at the position of rock layers. Absolute age is the numeric age of a layer of rocks or fossils.
