Help me create a marking scheme$/$answer this past paper thanks!

Suppose that the demand for sweets measured in kilograms is given by Q$^($D$)=6-2$P$,$ and the supply of sweets is given by Q$^($S$)=2$P$-2.$ The government legislates a $1$ tax on a kilogram of sweets, to be collected from the buyer. What is the price paid by buyers and the price received by sellers after the introduction of the tax?

a$.$ Buyers pay $2\mathrm{.}5$ and sellers receive $1\mathrm{.}5.$

b$.$ Buyers pay $3$ and sellers receive $2.$

c$.$ Buyers pay $1\mathrm{.}5$ and sellers receive $2\mathrm{.}5.$

d$.$ Buyers pay $2$ and sellers receive $1.$

Suppose that the Edgeworth box below represents the amount of shortbreads and brownies available to Bill and Edward. Suppose also that the point A denotes the current allocation of shortbreads and brownies to Bill and to Edward. Which of the following statements best describes the allocations shown in the Edgeworth box?

a$.$ Changing the allocation from point A to point B is a Pareto improvement.

b$.$ Changing the allocation from point A to point C is a Pareto improvement.

c$.$ Changing the allocation from point A to point D is a Pareto improvement.

d$.$ Both statement b and statement c are correct.