Answer :

[tex]15\ cups-5\ cups=10\ cups-change\\\\\begin{array}{ccc}5&-&100\%\\\\10&-&p\%\end{array}\ |cross\ multiply\\\\\\5p=10\cdot100\\5p=1000\ \ \ |divide\ both\ sides\ by\ 5\\\\\boxed{p=200\ (\%)}\\\\Answer:\boxed{an\ increase\ of\ 200\%}[/tex]