You can do this mathematically by using the following variables: $T$ (the total cost of the items), $B$ (the cost of the bat), and $b$ (the cost of the ball).
We know that $T=B+b=\$1.10$, and we also know that $B=\$1.00+b$, we plugging this into our original equation, we have:
$T=\$1.00+2b=\$1.10\implies 2b=\$0.10 \\ \therefore b=\frac{\$0.10}{2}=\$0.05$
So we now know the ball costs $5¢$, so to get the price of the bat, we can put:
$B=\$1.00+\$0.05=\$1.05$
So we now know that the bat must cost $\$1.05$, and the ball costs $\$0.05$.
You could do this in excel by doing each of the calculuations in a cell, but that would simply be superfluous, it's quite easy to do this mentally, or on paper, as you can see.
Hope this clears things up for you.