math
posted by Emma on .
A computer store sold a total of 300 items last month. The store sold six times as many
hard drives as they did CDROM drives, and half as many floppy drives as hard drives.
Based on this information, how many of each item were sold?
A. 30 hard drives, 90 floppy drives, and 180 CDROM drives
B. 40 hard drives, 20 floppy drives, and 240 CDROM drives
C. 180 hard drives, 90 floppy drives, and 30 CDROM drives
D. 240 hard drives, 20 floppy drives, and 40 CDROM drives
could someone plz help!

H = hard drives
C = CDROM
F = floppy drives.
==================
H = 6C
F = (1/2)*6C = 3C
H + C + F = 300
Substitute 6C for H and substitute 3C for F and solve for C, then H, then F. 
A and B do not fit the required 6:1 hard drive/CD drive ratio. That leaves C and D
Apply the hard/floppy ratio criterion (1:2) to see which it is. 
Let's read the question carefully.
The store sold six times as many
hard drives as they did CDROM drives . . .
That narrows your choices to two of the answers.
The next part:
half as many floppy drives as hard drives . . .
Which of the two meets that criterion? 
the answer would be(C)

Right.

thanks everyone!