This is my solution in perl

# Write your code here
my (`$x1, $`v1, `$x2, $`v2) = @_;    
if( `$v1 > $`v2 && (`$x2 - $`x1) % (`$v1 - $`v2) == 0)   {
    return "YES";
}else{
    return "NO";
}