:algebra, prealgebra, pre-algebra, number, fraction,
denominator, common denominator

:operation, common denominator

:, Find Common Denominator

:<TD ALIGN=LEFT style="text-align:center;" HEIGHT=30 NOWRAP>
 <INPUT TYPE=TEXT NAME="formula" SIZE=25 MAXLENGTH=100 VALUE="2/3 + 7/8, 5/9"></TD>
 <TD ALIGN=RIGHT VALIGN=center NOWRAP>
 $submit1
