2v+9=8v+21

Question

I need an explanation on how to get the answer

Answer 1

1. Draw a vertical line through the equal sign (separates the equation into two, equal, portions). 

 

2. Simplify both sides.  Use PEMDAS.  This equation is already simplified.

 

3. Move all variable to one side.  You have 2v on one side, and 8v on the other.  You need to "move" one of them, by "undoing" it.  Think about what would make a 2v go away.  Or you could do undo the 8v.  Personally, I'd move the 2v.

 

4. Isolate the variable.  Use SADMEP.  It's the reverse of PEMDAS.  This is called "Inverse Operations".  First you will have to get rid of the addition stuff, and THEN you get rid of the multiplication stuff.

 

That's the explanation.  I'm pretty sure you can do the actual math.

Answer 2

2v+9 = 8v+21 can be rearranged to have the unknown variable on just one side. Lets move the 2v to the right.

 

Whenever a term crosses the equal sign, its sign changes (from +ve to -ve or vice versa).

 

So, 9 - 21 = 8v - 2v

        -12  = 6v

 

Divide both sides by 6, so v is left.

 

So, v = -12 / 6 = -2