4) A radioactive isotope is decaying at a rate of 20% every hour. Currently there are 100 grams of the substance.
a) How much is left after 1 hour?

dont trust me im no expert these losers made me fail a test bro this sucks

step-by-step explanation:

b. y = 4x - 2

step-by-step explanation:

to find a parallel equation to an equation, make sure both equations have the same slope but different y-intercepts.

y = 4x + 1

4 = slope

1 = y-intercept

y = 4x - 2

4 = slope

-2 = y-intercept

they both have the same slope but different y-intercepts, so, b. is the correct answer.

and to check your work, you can graph both equations. : )