Divide 7-j\10 divide j-7\15

Question

Divide 7-j\10 divide j-7\15

Answer 1

If the problem is  (7-j)/10 divided by (j-7)/15  then the way to divide one fraction by another is to invert (or take the reciprocal of) the second fraction and then multiply the two fractions.  This leads to  

 

[(7-j)/10] * [15/(j-7)]  

 

Note that (7-j) is the negative of (j-7), meaning (7-j) = -(j-7).  So if you replace the (7-j) in the first fraction with -(j-7) then the two (j-7) terms will cancel leaving you with  

 

[-1/10] * [15/1] = -15/10 = -3/2