My 4th-grade niece is asking how many A's does it take to bring up a C?

1- 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.2- 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 the first question?

Need showing work for this problem 56.25 ×25.80

Can someone me find the original price? the discount is 5% and the sale price is $68.40