# Quantity supplied & demanded equation with tax

Here's the simple question I can't get my head around :(

QD= 120-P
QS= 2P-10
Tax= 25 euro per unit


How much does the government receive?

The demand curve shifts from the $Q^{D}=120-P$ (red line) to $Q^{D,tax}=120-(P+25)$ (green line). The supply curve is unchanged (blue line).
The new equilibrium quantity is 60 (instead of 76.667 in the case with no tax), and the revenue is equal to the unit tax times the quantity $25\times60=1500$, which is equal to the area of the orange rectangle.