did Claire buy?

[sanju09]

Claire paid a total of $1.60 for stamps, some of which cost $0.20 each, and the rest of which cost $0.15 each. How many 20-cent stamps did Claire buy?

(1) Claire bought exactly 9 stamps.

(2) The number of 20-cent stamps Claire bought was 1 more than the number of 15-cent stamps she bought.


[spoiler]Source: https://gmat.practicetests.teachstreet.com[/spoiler]

[Rich@VeritasPrep]

.20X + .15Y = 1.60 (where X is the number of 20-cent stamps and Y is the number of 15-cent stamps).

You want to find the value of X ...

(1) tells you that X+Y=9. This equation, along with the one from the prompt, gives you two independent equations with two variables. You can find the values of both X and Y. SUFFICIENT

(2) tells you X=Y+1. Again, gives you two independent equations with two variables. You can find the values of both X and Y. SUFFICIENT

Ans: D