The tango is danced in pairs, each consisting of one man and one woman. At a dance
evening no more than 50 people are present. At one moment 3/4 of the men are dancing with
4/5 of the women. How many people are dancing at that moment?
(A) 20 (B) 24 (C) 30 (D) 32 (E) 46
Arithmetic is numbers you squeeze from your head to your hand to your pencil to your paper till you get the answer.
Carl Sandburg
The difference between a two-digit number and the number obtained by interchanging the digits is 36. What is the difference between the sum and the difference of the digits of the number if the ratio between the digits of the number is 1 : 2 ?