Changes in demand and supply
Increase in demand and a decrease in supply

An increase in demand shifts the demand curve to the right from DD to D1D1.  The price increases and the quantity increases. A decrease in supply shifts the supply curve to the left from SS to S1S1and causes an increase in the price and a decrease in the quantity.

The combined impact of an increase in demand and a decrease in supply is an increase in the  equilibrium price. The impact on the equilibrium quantity is, however, uncertain since an increase in demand increases the quantity, ceteris paribus,  while a decrease in supply reduces the quantity.

The equilibrium quantity could riseremain the same, or fall, depending on the relative magnitudes of the change in demand and supply.