To find out how many cups of almonds Luis will need when using 3 cups of chocolate chips, we can set up a ratio based on the recipe.
The recipe states that for every 3/4 cup of chocolate chips, 1/8 cup of almonds is used.
First, let's find out how many sets of 3/4 cups are in 3 cups of chocolate chips:
\[ \text{Number of sets} = \frac{3 \text{ cups}}{3/4 \text{ cup}} = 3 \times \frac{4}{3} = 4 \]
Now that we know there are 4 sets of 3/4 cup in 3 cups, we can find out how many cups of almonds are needed:
\[ \text{Almonds needed} = 4 \times \frac{1/8 \text{ cup}}{1} = 4 \times \frac{1}{8} = \frac{4}{8} = \frac{1}{2} \text{ cup} \]
Thus, Luis will need 0.5 cup of almonds.
The correct answer is 0.5 cup.