LEAVING A TIP In Exercises $83-85$, use the following information. You and a friend decide to leave a $15 \%$ tip for restaurant service. You compute the tip, $T,$ as $T=0.15 C,$ where $C$ represents the cost of the meal. Your friend claims that an easier way to mentally compute the tip is to calculate $10 \%$ of the cost of the meal plus one half of $10 \%$ of the cost of the meal.
Write an equation that represents your friend's method of computing the tip.