1) Given that the meal cost $18.86 and there was an inclusion of 15% of this as a tip we can find the original cost, using an equation:
[tex]\begin{gathered} x(1+0.15)=18.86 \\ 1.15x=18.86 \\ \frac{1.15x}{1.15}=\frac{18.86}{1.15} \\ x=16.4 \end{gathered}[/tex]Note that the factor (1 +0.15) refers to the 15% added to the original cost. Dividing both sides, we get the original cost.
2) Thus, the original cost was $16.4
