Expert: Richard J. Raridon - 8/27/2009

Question
3(a-6)     4(a+6)
______  _  ______

 10         6        

Not sure how to do this one either.  He has about 12 of this style to do.

Answer
Simplier to write it 3(a-6)/10 - 4(a+6)/6
you can multiply each term by 30 to get 9(a-6) -20(a+6) = -11a-174
and then you have to put the 30 back in to get (-11a-174)/30.
The reason you use 30 is because that's the smallest number with both 10 and 6 as factors, called the LCD (lowest common denominator)