Salim has two kinds of food nutrients to add to a health drink. Nutrient A has $60\%$ filler materials by weight and Nutrient B has $40\%$ filler materials by weight. When added together, they had 240 pounds. Which equation models this relationship, where $x$ is the number of pounds of nutrient $A$ and $y$ is the number of pounds of nutrient $B$ ?

Question

$\begin{array}{1 1} (a)\; 0.4x+0.6y=240 \\(b)\;0.6x+0.4y=240 \\ (c)\; 40x+60y=240\\(d)\;60x+40y=240 \end{array}$