Thanks,

What country are you in? 

On american TV shows I have heard them call what you and I call a see saw, a teeter totter. ....

Look

Melody, a teeter-totter is a two-seated ride that swings back and forth 

A see-saw is a board that pivots in the center with a rider on each end

You have to add the areas of all 5 sides.

4 triangles and 1 square.

hint:

The area of a triangle is  1/2 * base * height.

You are turning the wrong fraction upside down :)

3/5n - 4/5 = 1/5n 

I'll show you very formally.

The equation must always balance, like a tetter totter (I think that is what Americans call them)

Whatever you do to one side you must do to the other side as well!

$\frac{3}{5}n-\frac{4}{5}=\frac{1}{5}n\\~\\ \frac{3}{5}n-\frac{4}{5}-\frac{1}{5}n=\frac{1}{5}n-\frac{1}{5}n\\~\\ \frac{2}{5}n-\frac{4}{5}+\frac{4}{5}=0+\frac{4}{5}\\~\\ \frac{2}{5}n=\frac{4}{5}\\~\\ \frac{2}{5}n\div \frac{2}{5} =\frac{4}{5}\div \frac{2}{5}\\~\\ n=\frac{4}{5}\div \frac{2}{5}\\~\\ n=\frac{4}{5}\times \color{blue}{\frac{5}{2}}\\~\\ n=\frac{2}{1}\\~\\ n=2$

                                                              a  =  2 + 3a + 6

subtract 3a from both sides —»      a –3a  =  2 + 6

                                                           –2a  =  8

divide both sides by –2                           a  =  –4 

You did it right.  It's just my personal preference to have the unknown on the left hand side. 

.

Thanks Nickolas :)

Mmm I can not see that you put that anywhere.

anyway, if you have to go I will see you later :)

My way does the whole thing all at once Nickolas. You do not need to worry about seperating the triangle an anything like that.

No, the parallel lines are  14 and 18   (the top and the bottom)

the perpendicular height is  7

No the parallel sides are the top and the bottom, They are running the same direction as each other. 

Ok Nicolas, try again,

How long are the parallel lines and what is the perpendicular height?

Then

What is the area?

Yes but perpendicular lines have to intersect at right angles!   That is 90 degrees