recategorized by
553 views
–1 votes
–1 votes

$A, S, M$ and $D$ are functions of $x$ and $y$, and they are defined as follows:

  • $A(x, y) = x + y$ 
  • $S(x, y) = x - y$
  • $M(x, y) = xy$ 
  • $D(x, y) = x/y$,

where $y \neq 0$.

A man travels three-fifths of distance $AB$ at a speed of $3a$, and the remaining at a speed of $2b$. If he goes from $B$ to $A$ and back at a speed of $5c$ in the same time, then:

  1. $1/a+1/b=1/c$
  2. $a+b=c$ 
  3. $1/a + 1/b=2/c$
  4. None of these
recategorized by

Please log in or register to answer this question.

Related questions