Question

Together three puppies and three adult dogs weight 60 pounds. two adult dogs and four puppies have a combined weight of 50 pounds. if each of the puppies has the same weight and each of the adult dogs has the same weight. how many pounds does one puppy weigh ?

please please help

Answer 1

Answer: one puppy weighs 5 pounds

Explanation:

Let the weight of one puppy be x and the weight of adult dog be y.

Then from the first statement

3x + 3y = 60

Also from the second statement

4x + 2y = 50

combining the two equations together , we have

3x + 3y = 60 ............................... equation 1

4x + 2y = 50 ................................. equation 2

solving the system of linear equation by elimination method , multiply equation 1 by 4 and equation 2 by 3 , we have

12x + 12y = 240 ................................ equation 3

12x + 6y = 150 ....................................... equation 4

subtract equation 4 from equation 3

6y = 90

y = 15

substitute y = 15 into equation 1 to get the value of x.

3x + 3 ( 15 ) = 60

3x + 45 = 60

3x = 60 - 45

3x = 15

x = 5

1 puppy weighs 5 pounds and 1 adult dog weighs 15 pounds