I use children's cunning eyes to detect that she loves us and doesn't mean to fight. What's the meaning of cunning

I use children's cunning eyes to detect that she loves us and doesn't mean to fight. What's the meaning of cunning

Children's cleverness

The definition, law and distribution of demand theorem; the condition and definition of budget equilibrium; the necessary condition of equilibrium market

The demand theorem is that under other conditions unchanged, the demand of a certain commodity changes in the opposite direction to the price, that is, the lower the price of the commodity, the greater the demand; the higher the price of the commodity, the smaller the demand
Budget equilibrium condition, budget line and indifference curve are tangent
Equilibrium market, supply = demand

Draw a picture to show the difference between the change of demand and the change of demand in the macro and micro of western economics,
It must be a picture

The change of demand q is relative to the change of price P when other conditions are fixed, while the change of demand is the relationship between the change of other conditions and the change of quantity when the price is fixed
 
One of my examples is s curve and the other is d curve

In economics, D means demand because demand. So why does Q mean demand?

Q refers to quantity; it can refer to output, supply and other quantitative things. D is commonly used in economics to represent the demand curve and demand function, just as s represents the supply function and supply curve