A number decreased by half of the number is four. What is the number?

This is so hard and it’s for a test

Olga used 100 ounces of flour to make 225 muffins. how many ounces of flour will be used to make 300 muffins?

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?