Because you are told the two are similar, find the ratio of them.
Side AB = ft and side EF is 25 feet.
This means the larger rectangle is 5 times larger ( 25 /5 = 5).
Area is in square units, so square the ratio: 5^2 = 25
The area of the larger rectangle is 25 times the area of the smaller one.
Area = 35 x 25 = 875 ft^2