A. 20% increase
B. 10% increase
C. 20% decrease
D. 10% decrease

Answer:
C. 20% decrease
Step-by-step explanation:
[tex]Saturday = 50\\Sunday =40\\\\50-40 =10\\\\\frac{10}{50} \times \frac{100}{1} \\= \frac{1000}{50} \\\\Cross \:cancel common \:factor; 50\\\\= 20[/tex]