About 400 marbles. You simply set up a proportion and solve it as I did in the photo attached.
Just subtract of 90 degrees and you get 68
Answer: 25 tables.
Step-by-step explanation:
5 • 10*2= 500 (10*2= 100, then 100 times 5)
2 • 10*1= 20 (10*1= 10, then times 2)
Therefore a cafeteria can seat 500 students. Each table had 20 seats.
Divide 500/20 and get 25.
Hope this helps