.Divide the sum of 13/5 and -12/7 by the product of -31/7 and -(1/2)

Here is another math questions. i will keep asking different questions. 4^2x=6

Triangle dog was rotated to create triangle d'o'g'. describe the transformation using details and degrees.

Since we have computer algebra systems that can solve polynomial division problems for us, why is it necessary to learn how to do these things by hand?