Let P be a positive number and suppose that the spot rate for one Australian dollar is P United States dollars. Let x be a positive number and assume that the United States dollar decreases by 100x % in Australian dollars.

a. Calculate the percentage increase for one Australian dollar in United States dollars in terms of x. Simplify your answer

b. Using your answer to (a), if the United States dollar decreases by 10% in Australian dollars, calculate the percentage change for one Australian dollar in United States dollars.