Help me please because i don't know this one,

Drag the tiles to match each measurement with an equivalent measurement.

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.

Ineed no it anyone can see this

In a singing competition, there are 150 participants. at the end of each round, 40% of the participants are eliminated. how many participants are left after n rounds?