Let [tex]b[/tex] be the number of baseball and [tex]k[/tex] be the number of basket ball.
We have the following system:
[tex]\begin{cases}b=4k\\b+k=25\end{cases}[/tex]
Substitute the first equation into the second:
[tex]4k+k=25 \iff 5k=25 \iff k=5[/tex]
which yields
[tex]b=4k=4\cdot 5 = 20[/tex]
So, there are 20 baseballs and 5 basketballs, meaning that there are 15 more baseballs than basketballs.
