3\sqrt{45}+2\sqrt{12}+5\sqrt{80}+3\ sqrt{108}

Find the solution of system of equation y= x-4 y=4x+2

Determine the difference: 3.2 × 1010 – 1.1 × 1010. write your answer in scientific notation.

School has 204 sixth grade students. if the sixth grade is 30% of the total school, how many students are in the middle school?