反比例的定義

inverse proportion means when a value of X increases,
the value of Y decrease, and vise versa.
for example, a large cake is divided equally to some children.
when the number of children increase, the size of the cake that
the children can get will be smaller.
ok?

反比例是指兩個variables有反向的關係，即是當其中一個variable 增加，另一個variable 就會減少。

例子:
當物價上升，人們對物品的需求量便會下降。
當中物價和需求量是兩個的variables，它們有反向關係，這就是反比例的意思。