Use reasoning to lead to the answer of the following question:
If the given two numbers are respectively 7% and 28% of a third number, then what percentage is the first of the second ?\nOptions:\n(A) 20%\n(B) 25%\n(C) 18%\n(D) 30%\n(E) none of these

(B)
Here, l = 7 and m = 28\nTherefore, first number = l/m x 100% of second number = 7/28 x 100% of second number = 25% of second number.

Final answer: (B)