Final answer:
Hector bought 80 stamps at 0.49 each after spending $43.40 at the post office, with the number of 0.49 stamps being four times the number of 0.21 stamps he purchased.
Step-by-step explanation:
Hector spent $43.40 at the post office buying two types of stamps. Let's denote the number of 0.21 stamps as x and the number of 0.49 stamps as 4x, since he bought four times as many 0.49 stamps as 0.21 stamps. We can write an equation to represent the total amount spent on both types of stamps:
0.21x + 0.49(4x) = 43.40
We then simplify and solve for x:
0.21x + 1.96x = 43.40
2.17x = 43.40
x = 43.40 / 2.17
x = 20
Since x is the number of 0.21 stamps, then Hector bought 20 of those. To find the number of 0.49 stamps, we multiply x by 4:
4x = 4(20)
4x = 80
Therefore, Hector bought 80 stamps at 0.49 each.