Answer: 24 band posters should be sold
Explanation:
First take the expression down to its simplest form;
= 5:4
Assume she sells 30 movie posters, her movies posters drop to;
= 100 - 30
= 70 movie posters
We need a number of band posters remaining that will give a ratio of 5:4 with movie posters.
In fraction form, the number of movie posters is;
= 5/9 because 9 would be the total number of both movie posters and band posters.
Create an expression to find the total number of posters if 70 are movie posters;
5/9x = 70
x = 70 รท 5/9
x = 126 posters
Number of band posters that should be left are;
= 126 - 70
= 56
Number of band posters that should be sold;
= 80 - 56
= 24 posters
The new ratio would be 70:56.