If element $A$ combines with element $B$ in a ratio of $1:2$ by mass,and element $A$ combines with element $C$ in a ratio of $6:4$ by mass,then by which law do elements $B$ and $C$ combine with each other?

According to Dalton’s atomic theory,an atom

One part of an element $A$ combines with two parts of another element $B$. Six parts of the element $C$ combine with four parts of the element $B$. If $A$ and $C$ combine together,the ratio of their weights will be governed by

Statement $1$: The mass ratio of hydrogen to oxygen in water obtained from rivers,wells,lakes,or seas is always $1:8$.
Statement $2$: In $1799$,the scientist Joseph Proust proposed the Law of Definite Proportions.

Which of the following examples illustrates the Law of Multiple Proportions?

Two elements $x$ and $y$ have atomic masses $14$ and $16$ respectively. They form a series of five compounds $A, B, C, D, E$ in which the ratio of $x$ to $y$ is $1:2:3:4:5$. If compound $A$ contains $28$ parts by weight of $x$ and $16$ parts by weight of $y$,then in compound $C$,how many parts by weight of $x$ will combine with $24$ parts by weight of $y$?