I’m doin corrections and i need bc i don’t understand

The price of a coat increased from $78 to $92. what is the price increase percentage?

Can someone me and do the problem plz so i can understand it more better

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?