In the problem 4 times 12 equals 48 which numbers are the factors

The sixth grade art students are making a mosaic using tiles in the shape of right triangles.each tile has leg measures of 3 centimeters and 5 centimeters.i f there are 200 tiles in the mosaic what is the area of the mosaic.

Bring the fraction a/a-4 to a denominator of 16-a^2

4+(2+x) can you me solve this problem