Your question is incomplete.
3(3b+2)=-30 perform indicated multiplication on left side...
9b+6=-30 subtract 6 from both sides
9b=-36 divide both sides by 9
b=-4
Hey Jinx :)
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Note that a decay has a rate between 0 and 1, and a growth as a rate of 1 or higher.
y = 1/2(1 + 0.03)^t → y = 1/2(1.03)^t (Rate is more then 0) GROWTH
y = 0.3(0.95)^t → (Rate is between 0 and 1) DECAY
y = ((1+0.03)^1/2)^2t → y = y = 1.014^2t (Rate is more then 0) GROWTH
y = 200(0.73)^t → (Rate is between 0 and 1) DECAY
y = 4(1/4)^t → (Rate is between 0 and 1) DECAY
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Hope This Helped! Good Luck!
They are similars because If you see the picture