I need help understanding this circuit can someone please ex

I need help understanding this circuit, can someone please explain this to me mathematicallly through circuit equations?

Solution

It is the project for night activated lamp (or) automatic street light.

whenever light will fall on the LDR (light dependent resistor), the resistance of the LDR will decrease and total current will pass throuh the LDR then the LED will not Glow. If we prevent the light then the resistance of the LDR will increase so total current will pass through the LED and the LED will glow.