First sort out the facts.
X= Total Population of City
0.27(X)= Voters that are less than 65 years old
0.17(X)= Voters that are 65 or older
X - (0.27 + 0.17)X= Non-Voters of All Ages != (1.00 - 0.24)X = Non-Voters of All Ages
No initial population...
I don't understand the problem to be honest. I would say no.