Let
be the number of baseball and
be the number of basket ball.
We have the following system:
![\begin{cases}b=4k\\b+k=25\end{cases}](https://img.qammunity.org/2021/formulas/mathematics/college/5pjcicgd9cbhi2yrnp2fp5pjxp0whuvz4d.png)
Substitute the first equation into the second:
![4k+k=25 \iff 5k=25 \iff k=5](https://img.qammunity.org/2021/formulas/mathematics/college/obog8x0tajb00mu5kdnw6t0ywv3vvb82xd.png)
which yields
![b=4k=4\cdot 5 = 20](https://img.qammunity.org/2021/formulas/mathematics/college/ddbolhxjnnjauyb1r02rzda3c85r7tcsbp.png)
So, there are 20 baseballs and 5 basketballs, meaning that there are 15 more baseballs than basketballs.