Answer:
Let X represent Nick's age and Y represent Sara's age.
Then, it is given that: Nick is four years older than Sara.
We write the statement as:
or 
The only ordered pairs (X,Y) which satisfy the equation are: (0,-4) and (4,0) as you can see in the graph also.
In the graph X axis represents the age of Nick's age and Y-axis represent the age of Sara's age and the line Y=X-4 represents the relationship between the age of both.
11/2 divided by $0.99 is $<span>1.51</span>
Use Law of Cooling:

T0 = initial temperature, TA = ambient or final temperature
First solve for k using given info, T(3) = 42

Substituting k back into cooling equation gives:

At some time "t", it is brought back inside at temperature "x".
We know that temperature goes back up to 71 at 2:10 so the time it is inside is 10-t, where t is time that it had been outside.
The new cooling equation for when its back inside is:

Solve for x:

Sub back into original cooling equation, x = T(t)

Solve for t:

This means the exact time it was brought indoors was about 2.5 seconds before 2:05 PM
Ok so first we find the equation that equals one variable.
2y = -x + 9
3x - 6y = -15
We solve for y.
2y = -x + 9
y = -x/2 + 9/2
Then we plug in this y value into the other equation to keep only one variable so we can solve for it.
3x - 6y = -15
3(-x + 9/2) - 6y = -15
-3x + 27/2 - 6y = -15
-9y + 27/2 = -15
-9y = 3/2
-y = 3/18
y = -3/18
Then we plug in this numerical y-value into the first equation which we found out by solving an equation for y.
y = -x/2 + 9/2
-3/18 = -x/2 + 9/2
-84/18 = -x/2
-x = 9 1/3
x = -28/3
Your answer would be (-28/3, -3/18)
Hope this helps!
You didn't ask a question but its called a period