To do anything with fractions you need to find a common denominator, in this case lets say its 128. the 9 in the negative side would need to be multiplied by 8 like it's denominator making it 72. You would do the same to the other fraction giving you the fractions -72/128 and 144/128 from here you add to get 72/128 which is positive
-9/16+9/8= -0.5625 + 1.125(in the addition of opposite signs u should figure out the largest num and should substract the other numa nd assign the sign of the biggest nym)
(rounded to one decimal place)