Linear Programming Help needed!

A wall is to be built using 2 types of brick of equal thickness. The wall is to be at least 3 metres high and at least 100 metres long and the thickness of a single brick. The large type of brick is of height 10cm and length 20cm. The small type of brick is of height 5cm and length 10cm

Each large brick needs 0.5 litres of mortar. Each small brick requires 0.25 litres of mortar. There are 10000 litres of mortar available.

b) Write down a constraint on the numbers of each type of brick to ensure that there is sufficient mortar.

Large bricks cost 25p each and small bricks cost 5p each.

c)Formulate an LP to find how many bricks of each type to use to build the wall at minimum cost.

d) Use a graphical method to solve your LP. Interpret your solution.