Set Up and Solve a Proportion for Each Application Problem $$\begin{aligned}& \frac{4}{x}=\frac{10}{15} \\& 15 \cdot x=10 \cdot 4 \\& 15 \cdot x=40 \\& x=\frac{40}{15} \\& x=2 \frac{2}{3}\end{aligned}$$

Set up and solve a proportion for each application problem.
-Find the error in the following solution, and complete the solution correctly.
$$\begin{aligned}& \frac{4}{x}=\frac{10}{15} \\& 15 \cdot x=10 \cdot 4 \\& 15 \cdot x=40 \\& x=\frac{40}{15} \\& x=2 \frac{2}{3}\end{aligned}$$