F ∝ a If F = 15 when a = 3 find, a when F = 70

F is proportional to a

F=ka

When F=15 and a=3

k=F/a=15/3=5=> k=5

When F=70

a=F/k=70/5=14=>a=14

step-by-step explanation: a reaction is first order. if the initial reactant concentration is 0.0200 m, and 25.0 days later the concentration is 6.25 x 10-4 m, then its half-life is:

answer: 140

step-by-step explanation:

so just add all then it will be your answer but i am not pretty sur eif it is but hope this i am here to people