Answer:
x = 14
Step-by-step explanation:
Since they are similar triangles, their sides are proportional
12 : 15 :: 8 : x - 4
Product of extremes = Product of means
12 × ( x- 4 ) = 15 × 8
12x -48 = 120
12x = 120 + 48
12x = 168
x = 168/12
x = 14
Is that the full question, because it doesn't make sense to me :/
Answer: It will take 6 years for 7500 grams of X to reach 6900 grams.
Step-by-step explanation:
Expression for rate law for first order kinetics is given by:

where,
k = rate constant
t = age of sample
a = let initial amount of the reactant
a - x = amount left after decay process
a) for completion of half life:
Half life is the amount of time taken by a radioactive material to decay to half of its original value.


b) for 7500 g to reach to 6900 g


It will take 6 years for 7500 grams of X to reach 6900 grams.