Given an equation for an asymptote of \[y=$a\cdot x+\frac{1}{x-$b}\] $first=&compareequations('y',"$a*x",$submission,1); if ($first=~/^Error/) { return 'BAD_FORMULA'; } if ($first=~/true/) { return 'EXACT_ANS'; } $second=&compareequations('x',$b,$submission,1); if ($second=~/^Error/) { return 'BAD_FORMULA'; } if ($second=~/true/) { return 'EXACT_ANS'; } return 'INCORRECT';