The answer depends on the units used for the measurements given in the question.
Length times width will give you area. So this comes out to 156 square feet.
14.5 square meters.
13X12=156 sq ft.
400 square feet.
16' x 15' = 240 square feet.
A room that is 12 feet by 13 feet is 156 square feet in area
14.5 square meters.
156 square feet. (just multiply the two)
13X12=156 sq ft.
400 square feet.
525 square feet.
120 square feet.
252 square feet.
324 square feet.
130 square feet.
352 square feet.
140 square feet.
770 square feet.