First, get the multiple values of the terms (solve the two terms beside the mathematical operation)
#7(-4) = -28#
#9(-5) = -45#
Then add these two terms since both are negative values. and add the #-# sign in front of the answer because both the terms are negative.
#-28 + (-45) = -73#
#(-) + (-) =# add and put #(-)# infront of the answer.
#(-) + (+) =# subtract and put the sign of the highest term.
For example:
#(-4) + 6 = 2#
(here #6 > 4#. Since #6# has a #+# sign, we put a #+# sign for the answer)
#(-6) + 4 = -2 #
(here #6 > 4#. Since #6# has a #-# sign, we put a #-# sign for the answer)