Respuesta :

[tex]\begin{array}{ccc}7\ cakes&-&\£2.10\\\\10\ cakes&-&x\end{array}\ \ \ |cross\ multiply\\\\7\cdot x=10\cdot\ \£2.10\\\\7x=\£21.00\ \ \ \ |divide\ both\ sides\ by\ 7\\\\\boxed{x=\£3.00}\leftarrow answer[/tex]