Slope point form:
We need the slope "m" and a point (x₀,y₀)
y-y₀=m(x-x₀)
1)
we calculate the slope "m".
Given two points:
(x₁,y₁)
(x₂,y₂)
the slope "m" is:
m=(y₂-y₁) / (x₂-x₁)
In this case:
(4,10)
(6,11)
m=(11-10) / (6-4)=1/2
Now, we calculate the solpe point form.
(4,10)
m=1/2
y-y₀=m(x-x₀)
y-10=(1/2)(x-4)
we make the standard form
y-10=x/2 - 2
Lowest common multiple=2
2y-20=x-4
-x+2y=-4+20
-x+2y=16
Answer: -x+2y=16
Transitive property I believe
As we already have the model that describes the change of the population in Italy in terms of the years that have elapsed, we only have to replace the conditions that are requested in that equation.
Therefore to find the population of Italy in the year 2000 (t = 10 years) substitute t = 10 in the equation and have:

million people
To find the population of Italy in 2008 (t = 18 years)
substitute t = 18 in the equation and have:

million people
To predict the population in Italy for 2015 and 2020 with this model, we substitute in the equation t = 25 and t = 30
t = 25
million people
t = 30
million people
Because you're trying to make them congruent, equal the two expressions to each other.
So, for #10 you would equal them so it would look like this.
2x+2=5x-19
Then you would just go ahead and simplify
2x+2=5x-19
-2x -2x
---------------
2= 3x -19
+19 +19
---------------
21=3x
--- ----
3 3
x=7
This means that x should be 7. You can check this just by plugging it in
2x+2
2(7)+2 = 16
5x-19
5(7)-19= 16
Same with #11.
x+8=3x-14
-x -x
--------------
8=2x-14
+14 +14
--------------
22=2x
--- ----
2 2
x=11
Check.
x+8
11+8= 19
3x-14
3(11) - 14 = 19
13x u add parentheses since two negatives positive