X=Tom´s age
y=Tim´s age.
we suggest this system of equations:
x+y=21
(x+3)=2(y+3)
We solve this system of equations by susbstitution method.
x=21-y
[(21-y)+3]=2(y+3)
24-y=2y+6
-y-2y=6-24
-3y=-18
y=-18/-3=6
x=21-y
x=21-6=15.
Answer: Tom is 15 years old, and Tim is 6 years old.
Answer:

Step-by-step explanation:
The time constant of the element X is:


The decay function has the following form:




Answer:
4 lol
Step-by-step explanation:
6:3 = 6/3 = 2
13 to 4 = 13:4 = 13/4 = 3.25
19/2 = 9.5
15 to 10 = 15:10 = 15/10 = 1.5
8:2 = 8/2 = 4
From the least to the greatest:
15 to 10 , 6:3, 13 to 4, 19/2
I hope this explains it.