The question is in the attachment.
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x= 4

Step-by-step explanation:

Intersecting Chords Formula:

(segment piece) x (segment piece) =   (segment piece) x (segment piece)

10*6 = 15*x

60 = 15x

Divide each side by 15

60/15 = 15x/15

4 =x

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)