1.the new number , 200 , is 400 less than the original number . what is the precent change ?
a: 0.6%
b: 1.5%
c: 66%
d: 150%
2.the attendance at a seminar in year 1 was 500 . in year 2 , the attendance changes by 100 . what was the precent change in attendance?
a: 0.2%
b: 0.4%
c: 20%
d: 40%

Need ! give step by step solutions on how to solve number one \frac{9-2\sqrt{3} }{12+\sqrt{3} } number two x+4=\sqrt{13x-20} number three (domain and range) f(x)=2\sqrt[3]{x} +1

Is this a polynomial function? i need to know asap

1- is the product of two rational numbers irrational or rational? first, make a hypothesis by multiplying two rational numbers. then, use variables such as x=a/b and y=c/d and the closure property of integers to prove your hypothesis. 2- what do you think the product of a nonzero rational number and an irrational number is? is it rational or irrational? make use of variables, the closure property of integers, and possibly a proof by contradiction to prove your hypothesis. 3- why do we have to specify that the rational number must be nonzero when we determine what the product of a nonzero rational number and an irrational number is? if the rational number were 0, would it give us the same result we found in part b?