Equilibrium price and quantity - consumer and producer surplus
Equating supply and demand we obtain the equilibrium

$$P^* = 75, Q^*=100$$

The corresponding diagram is


Consumer Surplus is the area of triangle $B-E-C$ so

$$CS = \frac 12 \cdot (100-75)\cdot 100 = 1250$$

Producer Surplus is the area of the triangle $B-E-A$ so

$$PS = \frac 12 \cdot (75-20)\cdot 100 = 2750$$