SOLUTION: Cheryl is redoing her bathroom and has selected ceramic tiles for the 5 foot by 8 foot bathroom floor. The plain 6-inch square tiles cost 75 cents each; the decorative 2-inch squar

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Question 1105577: Cheryl is redoing her bathroom and has selected ceramic tiles for the 5 foot by 8 foot bathroom floor. The plain 6-inch square tiles cost 75 cents each; the decorative 2-inch squares cost $1.25 each. If Cheryl's total cost for the flooring is to be $246, how many decorative tiles can she get?
A) 108
B) 148
C) 209
D) 241
I know the answer is A but I have no idea why. Thanks!

Answer by greenestamps(13200) About Me  (Show Source):
You can put this solution on YOUR website!


Let x be the number of decorative 2x2 inch tiles
Let y be the number of plain 6x6 inch tiles

In square inches, the area of each decorative tile is 4; the area of each plain tile is 36; the area of the whole floor is 60*96 = 5760:
4x%2B36y+=+5760
(1) x%2B9y+=+1440 [divide by the common factor of 4]

The cost of each decorative tile is $1.25; the cost of each plain tile is $0.75; the total cost is $246:
1.25x%2B.75y+=+246
(2) 5x%2B3y+=+984 [multiply by 4 to get rid of the decimals]

The problem asks for x, the number of decorative tiles she can get; so use elimination with equations (1) and (2) to eliminate y. Multiply equation (2) by 3 and subtract equation (1):
15x%2B9y+=+2952
x%2B9y+=+1440
14x+=+1512
x+=+1512%2F14+=+108