Given :
a restaurant customer left a $1.95 as a tip.
The tax = 5%
the tip was 15% of the after-tax cost
So, the information that not needed is the tax
Let the total bill = x
so, 15% of x = 1.95
[tex]\begin{gathered} 0.15\cdot x=1.95 \\ \\ x=\frac{1.95}{0.15}=13 \end{gathered}[/tex]so, the total bill = $13