Answer:
£16.50
Step-by-step explanation:
[tex]x \times (1+\frac{10}{100} )=18.15[/tex]
[tex]x \times \frac{110}{100} =18.15[/tex]
[tex]\frac{110}{100} x=18.15[/tex]
[tex]1.1x=18.15[/tex]
[tex]\frac{1.1x}{1.1}=\frac{18.15}{1.1}[/tex]
[tex]x=16.5[/tex]
