Answer:
24 cups of green you'll need.
[tex]\\[/tex]
Step-by-step explanation:
[tex] \mathsf{ \frac{2}{3} \: black \: cups \: need \: = \green{4 \: quarts} }[/tex]
[tex] \mathsf{ 1\: black \: \: cup\: needs \: = \green{ \frac{4}{ \frac{2}{3} } \: quarts} } \\ = \mathsf{\green{ \frac{4 \times 3}{2} }} \\ = \mathsf {\green{ 6 \: quarts}}[/tex]
[tex] \mathsf{ 4 \: black \: \: cups \: need \: = \green{4 \times 6 \: quarts} } \\ \green{ \boxed{\mathsf{ 24 \: cups}}}[/tex]