Multiply the amount of fluid ounces in a mug by the amount of mugs Annie needs to fill:
\(16 \times 26 = 416\)
There are 32 fluid ounces in a quart. Divide the total amount of fluid ounces by the amount of fluid ounces in a quart:
\(416 \div 32 = 13\)
Annie will need 13 quarts of coffee to fill the mugs.