Question

LaDonna is running for city council. She needs to get four fifths 4 5 of her votes from senior citizens and 40 comma 00040,000 votes in all to win. How many votes does she need from voters other than the senior​ citizens?

Answer 1

She needs in total 40,000 votes, and from those 40,000, 4/5 need to be from senior citizens, now, 5/5 is a "whole", so 5/5 - 4/5 that leaves only 1/5.

therefore, of those 40,000 votes, 1/5 can be of non-senior citizens, how much is 1/5 of 40,000?  well, is just their product,

$\bf \cfrac{1}{5}\cdot 40000\implies \cfrac{40000}{5}\implies 8000$