Ionly need with justifying the step in solving the  problem. !

The question is:  Which method do you prefer ?

First of all, nobody can answer that for you, because it's your opinion and you haven't told us your opinion.

But look at it ! the first method eliminates parentheses right away, and each step is an application of a clear, simple arithmetic rule.  The second method has fractions and parentheses all over the place, and it looks so complicated that even the person who posted the first answer here doesn't completely recognize what's going on.

I know which method I would prefer.  But like it says, the correct answer is a matter of opinion, and my opinion might not be the same as yours.

step-by-step explanation:

the original amount doesn't ''re just looking for the time it takes for 1/2 of the substance to we have

(1/2) =)     take the ln   of both sides

ln (1/2)   = )   and we can write

ln(1/2) = ) lne     and lne   = 1     so we have

ln(1/2) = -.1092t     divide both sides by -.1092

t = ln(1/2)/-.1092 = about 6.347 days = about 6.3 days (rounded)

i can't read the graph

step-by-step explanation: