<PRE><B>Question 535931</B>
3*5=15
3*7=21
3*5*7=105
multiply 2/15x by 7x/7x
14x/105x^2
multiply -4/21x^2 by 5
-20/105x^2
(14x-20)/105x^2
factor out 2 in the numerator
2*(7x-10)/105x^2</PRE>