In a 100 m race, A can give B 10 m and C 28 m. In the same race B can give C:
18 m
20 m
27 m
9 m
Explanation:
A : B = 100 : 90.
A : C = 100 : 72.
B : C =$ \dfrac{B}{A} \times \dfrac{A}{C} $=$ \dfrac{90}{100} \times \dfrac{100}{72} $=$ \dfrac{90}{72} $.
When B runs 90 m, C runs 72 m.
When B runs 100 m, C runs$ \left(\dfrac{72}{90} \times 100\right) $m= 80 m.
$\therefore$ B can give C 20 m.