Question

Given A:B=3:7 and B:C=4:9 find A:C

Answer 1

`\begin{gathered} (A)/(C)=(A)/(B)*(B)/(C) \\ \text{Thus,} \\ A\colon C=A\colon B* B\colon C \end{gathered}`
`\begin{gathered} A\colon B=(A)/(B)=(3)/(7) \\ B\colon C=(B)/(C)=(4)/(9) \\ \text{Thus,} \\ A\colon C=(A)/(C)=(A)/(B)*(B)/(C) \\ A\colon C=(3)/(7)*(4)/(9) \\ A\colon C=(12)/(63)=(4)/(21)=4\colon21 \end{gathered}`

Hence, A:C is 4:21