Circuit that confuse me
This circuit is equivalent to the following:



simulate this circuit &ndash; Schematic created using CircuitLab
The ground symbol (the three lines that you see twice at the bottom of your schematic) indicates two things:

this is connected to every other ground symbol in the circuit, and
this is what we're calling zero volts.

The arrows pointing up with a number of volts written by them indicate two things:

this is connected to every other arrow with the same voltage in the circuit, and
There's a voltage source of x volts between here and ground.

The reason circuits are drawn like this is that, for complex circuits, it would get very confusing very quickly if you had to draw lines back to the voltage source for every single thing that was connected to ground. Imagine doing that for a PC motherboard's schematic!