SOLUTION: Carol's cat weighs 2 pounds. Doug's dog weighs 14 pounds. Both pets are gaining about a pound a month. If they keep on gaining weight like that, the dog will soon weigh three tim

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Question 515073: Carol's cat weighs 2 pounds. Doug's dog weighs 14 pounds. Both pets are gaining
about a pound a month. If they keep on gaining weight like that, the dog will soon weigh three times as much as the cat. How many pounds will the cat weigh then?
Found 2 solutions by Maths68, josmiceli:
Answer by Maths68(1474) About Me  (Show Source):
You can put this solution on YOUR website!
Cat = 2 lb
Dog = 14 lb
Let both gain x lb
(Dog + x)=3*(Cat+x)
14+x=3(2+x)
14+x=6+3x
x-3x=6-14
-2x=-8
-2x/-2=-8/-2
x=4
Cat = 2lb + 4lb = 6 lbs
Dog = 14lb + 4lb = 18 lbs
The cat wil weigh 6 pounds.

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let m = number of months
after the 1st weighing
Let c = cat's weight
Let d = dog's weight
+c%2Fd+=+%28+2+%2B+1%2Am+%29+%2F+%28+14+%2B+1%2Am+%29+
When the dog weighs 3 times the cat:
+c%2F3c+=+%28+2+%2B+1%2Am+%29+%2F+%28+14+%2B+1%2Am+%29+
+1%2F3+=+%28+2+%2B+1%2Am+%29+%2F+%28+14+%2B+1%2Am+%29+
Multiply both sides by +3%2A%28+14+%2B+m+%29+
+14+%2B+m+=+3%2A%28+2+%2B+m+%29+
+14+%2B+m+=+6+%2B+3m+
+2m+=+8+
+m+=+4+
The dog will weigh +14+%2B+m+=+18+ pounds
The cat will weigh +2+%2B+m+=+6+ pounds