What is the solution to (3 x 10^2) (5 x 10^5) written in scientific notation?

1.5 x 10^8
15 x 10^8
1.5 x 10^7
15 x 10^7

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.

Find the perimeter of the triangle with vertices  d(3, 4),  e(8, 7), and  f(5, 9). do not round before calculating the perimeter. after calculating the perimeter, round your answer to the nearest tenth.  

Factor the polynomial by its greatest common monomial factor.