Answer:
![0.50b+1.25h=20](https://img.qammunity.org/2020/formulas/mathematics/high-school/clrx3efircohbfz3shmo5613dt4ulrpxps.png)
Step-by-step explanation:
Let b be the number of balloons and h be number of party hats.
We have been given that balloons cost $0.50 each, so cost of b balloons will be 0.50b.
We are also told that party hats each cost $1.25, so cost of h party hats will be 1.25h.
Further, Joe wants to spend exactly $20 on the party supplies. We can represent this information in an equation as:
![0.50b+1.25h=20](https://img.qammunity.org/2020/formulas/mathematics/high-school/clrx3efircohbfz3shmo5613dt4ulrpxps.png)
Therefore, the equation
represents the number of balloons ( b) and the number of party hats ( h) that Joe can buy spending exactly $20.