9514 1404 393
Answer:
3 48-cent stamps
9 7-cent stamps
Explanation:
The number of 48-cent stamps Amy can use is less than 207/48 ≈ 4.3, so we can find the numbers by trial and error. We want ...
48a +7b = 207 . . . . . . postage in cents, where a, b are the numbers of stamps
b = (207 -48a)/7 = 29 4/7 -a(7 -1/7) = (29 -7a) +(a+4)/7
In order for b to be an integer, we must have (a+4) a multiple of 7. The least value of 'a' that will make this true is a=3. That value gives ...
b = (29 -7·3) +(3+4)/7 = 8 +1 = 9
Amy used 3 48-cent stamps and 9 7-cent stamps.