Question

1/7A=1/5B=1/3c..find A:B:C

Answer 1

1/7A=1/5B=1/3C
A:B:C=15:21:35

Answer 2

$\frac{1}{7A}=\frac{1}{5B}=\frac{1}{3C} \\ \\ \\ 105 \times \frac{1}{7A}=105 \times \frac{1}{5B}=105 \times \frac{1}{3C} \\ \\ \frac{105}{7A}=\frac{105}{5B}=\frac{105}{3C} \\ \\ \frac{15}{A}=\frac{21}{B}=\frac{35}{C} \\ \\ \\ \therefore\ A:B:C=\bold{15:21:35}$

Please inform me if I misunderstood the question.

Thank you. ;-))