First you have to get the equation into slope/intercept format: y = mx + b

So the slope m = 2, and the y-intercept b = -1.
b tells you where the line intersects the y axis. The slope is rise (vertical distance) over run (horizontal distance). I have attached my best attempt at drawing this without graph paper. The dotted line represents the inequality, and the solution set includes the values above the line which is why it is shaded. Hope this helps!
First we need to have same units before comparing them. That is, either both of them are in cm or both of them are in mm. So if we need to convert 12.5 cm to mm, we know that 1 cm =10 mm. So we have to find out how many mm are in 12.5 cm. And let 12.5 cm =x mm. So to find the value of x , we set a proportion and solve for x. That is

The units cancel out and we do cross multiplication. That is

x=125
So 12.5 cm =125 mm. Therefore the correct proportion is C.
There are many strategies that can be used it really depends on what kind of questions you're answering.
Answer:3.1875
Step-by-step explanation: Simplifying
-3 + 8 + -8(7 + -2a) = 0
-3 + 8 + (7 * -8 + -2a * -8) = 0
-3 + 8 + (-56 + 16a) = 0
Combine like terms: -3 + 8 = 5
5 + -56 + 16a = 0
Combine like terms: 5 + -56 = -51
-51 + 16a = 0
Solving
-51 + 16a = 0
Solving for variable 'a'.
Move all terms containing a to the left, all other terms to the right.
Add '51' to each side of the equation.
-51 + 51 + 16a = 0 + 51
Combine like terms: -51 + 51 = 0
0 + 16a = 0 + 51
16a = 0 + 51
Combine like terms: 0 + 51 = 51
16a = 51
Divide each side by '16'.
a = 3.1875
Simplifying
a = 3.1875