An aquarium must have 4 large tanks for every 28 sharks. The aquarium manager would like to adopt 49 sharks. How many large tanks would they need?

To determine how many large tanks are needed for 49 sharks, we can start by establishing the ratio of large tanks to sharks.

According to the information provided, there are 4 large tanks for every 28 sharks. We can express this as a ratio:

\[
\frac{4 \text{ tanks}}{28 \text{ sharks}} = \frac{1 \text{ tank}}{7 \text{ sharks}}
\]

This means that 1 large tank is required for every 7 sharks.

Now, to find the number of large tanks needed for 49 sharks, we can divide the number of sharks by the number of sharks that can be accommodated per tank:

\[
\text{Tanks needed} = \frac{49 \text{ sharks}}{7 \text{ sharks/tank}} = 7 \text{ tanks}
\]

Therefore, the aquarium manager would need **7 large tanks** for 49 sharks.