How do double shifts impact price and quantity?
When supply and demand both shift, either price or quantity will be indeterminate. When supply and demand move in the same direction, price is indeterminate. That is because an increase in supply decrease price while an increase in demand will increase price. Since the price axis moves in both directions, the net effect is based on which shift is stronger. Since that cannot be known, the price will be indeterminate. Since both shifts increase equilibrium quantity, the quantity will definitely increase.
Similarly, when supply and demand move in opposite directions, quantity is indeterminate because one shift will increase quantity and the other will decrease quantity.
The key to figuring out the impact of double shifts is to graph out both shifts and see what happens to the equilibrium price and quantity with each shift. If the shifts conflict, that axis is indeterminate.