Answer:
Umm let me see
Step-by-step explanation:
You work it backwards.
-- If there were 4 children and each child got 4 pieces,
then the children got (4 x 4) = 16 pieces altogether.
-- That's what was left after he took 2 pieces for himself.
So he started with (16 + 2) = <em>18 pieces</em>.
This gives you, 4x + 5y = -25 as your final answer.
Answer:
6x=-60
Step-by-step explanation:
The mass of substance left after 7 days is 13.09 g
The mass of substance left, N is given by
N = N₀exp(-λt) where λ = decay constant and N₀ = initial mass of substance present = 24 g and t = time
Also, λ = 0.693/t' where t' = half-life of iodine = 8 days
So, λ = 0.693/t'
λ = 0.693/8
λ = 0.086625/day
Since the mass of substance left is N = N₀exp(-λt) and we require the mass of substance after t = 7 days,
N = N₀exp(-λt)
N = 24 gexp(-0.086625/day × 7 days)
N = 24 gexp(-0.606375)
N = 24 g × 0.5453
N = 13.09 g
So, the mass of substance left after 7 days is 13.09 g
Learn more about radioactive decay here:
brainly.com/question/23705307