Answer: 480 people attended this circus on Saturday.
Explanation:
The amount of people that attended the Circus on Friday is 3 fourths the amount of people that attended on Saturday.
Let x represent amount of people that attended on Saturday. It means that the number that attended on Friday is 3x/4
The total amount of people that attended this circus on both days is 840. Therefore
x + 3x/4 = 840
4x + 3x = 3360
7x = 3360
x = 3360/7
x = 480