We have been given that Joanie wants to mail a package that requires $1.04 in postage.
She has only 5-cent and 6-cent stamps.
Let us assume that she uses x 5-cent stamps and y 6-cent stamps. Therefore, we can set up an equation:
![5x+6y=104](https://img.qammunity.org/2019/formulas/mathematics/high-school/8ol5knl7qsfksfi0vi3ekt1bel6y1hsqqm.png)
We need to figure out integer values of x and y such that their sum, that is, (x+y) is minimum.
In order to do so, we would be requiring at least four 5-cent stamps.
Therefore, number of 6-cent stamps would be:
![5(4)+6y=104\\20+6y=104\\6y=84\\y=(84)/(6)=14](https://img.qammunity.org/2019/formulas/mathematics/high-school/64nbaqga0ln553yvponv8uoq9ojiqi0y5j.png)
Therefore, the smallest number of stamps would be 14+4 = 18 stamps