Amount of tip she gave,
[tex]T = 15\times 0.20\\\\T =\$3[/tex]
Amount of tax given :
[tex]Tax=15\times 0.09\\\\Tax = \$1.35[/tex]
So, total amount she paid is :
Total = Actual cost + Tip + Tax
Total = $(15 + 3 + 1.35 )
Total = $19.35 .
Therefore, total amount she paid is $19.35 .
Hence, this is the required solution.