A’s marks is 10% less than that of B and C’s marks is 10% more than that of B. By what percent is A’s marks less than that of C?
Solution
Let B’s marks be 100
A’s marks is 90
C’s marks is 110
$\therefore$ A’s marks is $\dfrac {20}{110}=\dfrac {2}{11}=\dfrac {200}{11}\%$ or $18\dfrac{2}{11}\%$ less than that of C.