The two methyl groups pointing down on the left should consist of a dash and a wedge, giving it the bond angle of 109.5 degrees. It could be a really awful Fisher projection also :)
Please look at picture. It seems as though the bond angles are wrong for C5H10O. Is it common in organic chemistry to not respect bond angles?
I had to think for a moment to spot the problem - it was so obvious to me what the left part if the image is intended to mean (see ChiralWaltz post), that it required an effort to see it as 2D.
It is common in organic chemistry to draw molecules as projections, as they are (almost) never flat. Dashes and edges are used only when the molecule drawn without them is ambiguous. Here, when you know it is a projection, it doesn't matter which carbon goes up and which goes down. On top on that, these projections are almost never perfect (there is no right angle in the molecule), but are accepted as long as it is clear what is the intended spatial arrangement of the atoms.