The half life of a certain substance is about 4 hours. The graph shows the decay of a 50 gram sample of the
substance that is measured every hour for 9 hours.

answer:   b

step-by-step explanation:

x2 = 16

x can not be a negative number because 16 is positive

the only answer would be positive 8  

10 down (bang1)

5 up

5down (2)

2.5 up

2.5 down (3)

1.25 up

1.25 down (4)

now add them up : )

hoped i lol

step-by-step explanation:

left be aligning the decimal points is required to not required see the number of digits to the right