The correct equation is 8.7 + b = 54.6
because it is given that measure of side a is 8.7cm, in all other equations the values of a is different.
from the first equation we can find the value of b, that is
b = 54.6 - 8.7 = 45.9
so, value of b is 45.9cm
To represent all the possible answers this would represent you would write the following inequality:
z < 34
This tells us that any number less than 34 is a possible solution. We call all of the answers that are possible a solution set.