well, the order is $159, so say that's the 100%, we know the delivery charge was 10 bucks.
[tex]\begin{array}{ccll} amount&\%\\ \cline{1-2} 159&100\\ 10&x \end{array}\implies \cfrac{159}{10}=\cfrac{100}{x}\implies 159x=1000 \\\\\\ x=\cfrac{1000}{159}\implies x\approx 6.29[/tex]
