The general way to work this out is to solve the general expression for
the remaining quantity versus half-life, using logarithms. But that's not
necessary with these numbers.
Look at the numbers:
-- 3 mg is 1/4 of 12 mg.
-- 1/4 is the product of (1/2) x (1/2).
-- So the 3 mg is what's left of 12 mg after 2 half-lives.
The 26 minutes must be two half-lives.
-- The half-life of that substance is 26/2 = <em>13 minutes</em>.
Go Maggie !
Preserved the size because 12inchs is = to 1 ft.
Yes, 13 is the remainder.
See dat pic for full solution.
Your answer will be 5xplus10
(2(-2)+9(5)-5)-(6(-2)-4(5)+2)
(-4+45-5)-(-12-20+2)
(45-9)-(-32+2)
36+30
66
