What is the largest value you can find in the interval (-5,-1)

(-5,-1) is aka -5<x<-1

This means -2 is the largest value you can find.

Perhaps that is if you are on a line graph, or if you are putting this on a line graph put an open circle (○) on -1 and -5 and draw a line in between the numbers. That's also if you are talking about real numbers and not integers this question is a bit too broad for me to actually figure out the true answer.

so, converting firstly the mixed fractions to improper fractions and then "adding".