Suppose there are three pipes filling a tank. The first pipe can fill the tank in 5 hours. The second pipe can fill the tank in 8 hours. The third pipe can fill the tank in 7 hours. Suppose the pipes run for $5 \times 8 \times 7=280$ hours. How many tanks can the first pipe fill? How many tanks can the second pipe fill? How many tanks can the third pipe fill?

Step 1 ：Suppose there are three pipes filling a tank. The first pipe can fill the tank in 5 hours. The second pipe can fill the tank in 8 hours. The third pipe can fill the tank in 7 hours.

Step 2 ：Suppose the pipes run for \(5 \times 8 \times 7=280\) hours.

Step 3 ：We are asked how many tanks the first pipe can fill. Since the first pipe can fill the tank in 5 hours, and the pipes run for 280 hours, we can calculate this by dividing the total hours by the hours needed for the first pipe.

Step 4 ：\(\frac{280}{5} = 56\)

Step 5 ：Final Answer: The first pipe can fill \(\boxed{56}\) tanks.