Question

TWO LENGTHS ARE IN RATIO 3:7. SECOND LENGTH IS 42 CM . FIND OTHER LENGTH WITH FORMULA

Answer 1

then 3=x and 7=42
$\frac{3}{7} = \frac{x}{42 }$
$3 = \frac{x}{42} \times 7$
$3 = \frac{x}{6} \\ x = 3 \times 6 = 18$

Answer 2

One length =42cm.
One length =3x.
another length =7x.
7x-3x=42
4x=42
x=42/4
x=21/2
x=10.5.