Why was Mrs shaw tidying up the house? (from say the right thing by g.c Thornley)

Why does law of demand slope downward from left to right ?

Sergei says, “I am happy that my words have taken effect.” Why does he say so? Is he right in saying this?

What is the number place of G from right side ?

Mr. Das started his journey from his house straight to his friend's house at a distance of 12 km. On returning he walked 8 km in the same route and turned right and walked 4 km, then he turned to his left and walked 4 km. Finally he turned to his left and walked 2 km. How far was he from his house?