Answer:
(2400+420).
Step-by-step explanation:
We can break this into the same pattern as the other numbers, giving us:
(60×40)+(60×7)
When we multiply these we get:
(2400+420).
Given the equation:

You know that the radioactive substance has this half-life (in years)

And:

Therefore, you can rewrite the equation in this form in order to find "k":

Solve for "k":
answer: 4s+4
(s+12)+(3s-8) distrubute --> s+12+3s-8
comibine like terms 4s+4
hopfully this helped :)
I believe the answer is 18 gallons.
6/9-4/9=2/9
Best Answer: Eighteen.... yes, I read it right. *sigh*
First convert 2/3 into ninths.
2/3 = 6/9
Therefore 2/9 is equal to 4 gallons...
Therefore 1/9 is equal to 2 gallons...
9 multiplied by 2 gallons is 18 gallons.