Let P(n) be the statement that a postage of n cents can be formed using just 4-cent and 7-cent stamps. Use strong induction to prove that P(n) is true for all integers greater than or equal to some threshold x.

True for n = 18, 19, 20, 21

Step-by-step explanation:

a postage of cents; where . ( are the number of 4-cent stamps and are the number of 7-cent stamps)

For is true.

This is a possibility, if

Similarly for :

the number of the people going.

step-by-step explanation:

the cost to buy one movie ticket is $7. if the total cost for the movie is a function of how many people go, then the input is : the number of the people going.