Question

If the compound ratio of $7:5$ and $8:x$ is $84:60$ find $x$.

Answer 1

From question,
Compound ratio of $7:5$ and $8:x=84:60$
We know that, compound ratio of $a:b$ and $c:d$ is $ac:bd$
$⟹(7\times 8):(5\times x)=84:60$
$⟹\frac{56}{5x}=\frac{84}{60}$
$⟹\frac{56}{5x}=\frac{7}{5}$
$⟹5x\times 7=56\times 5$
$⟹7x=56$
$⟹x=\frac{56}{7}=8$
Therefore, $x=8$