Answer :

He left $4.50. You just find 15% which is 10% and then 5% added on.
luana
[tex]multiply\ 15\%\ by\ a\ cost\ of\ bill\\\\ 15\%*30=\frac{15}{100}*30=0,15*30=4.5\\\\ He\ left\ 4.5\$\ for\ tip.[/tex]